Inogen Inc 10-K

ITEM 7. MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS The following discussion and analysis of the financial condition and results of our operations should be read in conjunction with the consolidated financial statements and related notes included elsewhere in this Annual Report on Form 10-K. This discussion contains forward-looking statements that involve risks and uncertainties. Our actual results could differ materially from those discussed below. Factors that could cause or contribute to such differences include, but are not limited to, those identified below, and those discussed in the section titled “Risk Factors” included elsewhere in this Annual Report on Form 10-K. COVID-19 pandemic and related PHE The novel coronavirus outbreak of COVID-19 has had and likely will continue to have significant adverse effects on businesses and healthcare institutions around the world. While it is not possible at this time to estimate the overall impact that the COVID-19 pandemic and related PHE could have on our business, the continued rapid spread of COVID-19, both across the United States and throughout much of the world, and the measures taken by the governments of countries and local authorities affected has adversely impacted and will likely continue to adversely impact our business operations, demand for our products, the manufacture or shipment of our products, and our financial condition and operating results. Our priorities during the COVID-19 pandemic and related PHE include protecting the health and safety of our employees and supporting our patients and customers. Given the COVID-19 impact to the respiratory system, oxygen therapy is prescribed by healthcare professionals for treatment and recovery for certain patients with COVID-19. We also believe stationary oxygen concentrators, and, secondarily, portable oxygen concentrators (POCs) could provide relief to global hospital systems by allowing appropriate patients to be treated in the home, such as patients early in the disease progression or those in recovery post hospital discharge, thus making room for more severe patients who need treatment in the hospital. However, the COVID-19 pandemic and related PHE adversely impacted our consolidated operating results in the second, third and fourth quarters of 2020. We experienced lower direct-to-consumer sales starting toward the end of the first quarter of 2020 and through the fourth quarter of 2020. We believe the social distancing, self-quarantine and related mandates and behaviors emanating from the COVID-19 pandemic and related PHE, including shelter-in-place orders, reduced travel, and lower consumer confidence reduced direct-to-consumer sales. While there was an initial surge in demand for oxygen concentrators by our home medical equipment (HME) providers worldwide early in the COVID-19 pandemic and related PHE, total business-to-business demand declined in the second, third and fourth quarters of 2020 due to lower retail sales, lower patient travel, physician offices limiting patient interactions for chronic obstructive pulmonary disease (COPD) patient referrals, HME providers minimizing patient interactions in response to the COVID-19 pandemic and related PHE, which includes replacing existing oxygen patient setups with POCs, and HME providers turning their purchasing focus to stationary oxygen concentrators to treat COVID-19 patients. Also, sales in Europe declined associated with the temporary closure and reduced operating capacity of certain respiratory assessment centers and continued tender delays in certain markets due to the COVID-19 pandemic. The COVID-19 pandemic and related PHE has also and could continue to lead to volatility in consumer access to our products due to government actions impacting our ability to produce and ship products or impacting consumers’ movements and access to our products. The COVID-19 pandemic and related PHE has caused and may continue to cause reduced demand for our products across all channels due to the global economic environment and reduced regular physician interactions and testing which could lead to a lower rate of diagnosis for long-term oxygen therapy. Additionally, while we initially planned for sales and marketing expansion in 2020, this was negatively impacted due to the COVID-19 pandemic and related PHE, which reduced the close rates on patients who contact us resulting in less efficient marketing spend, reduced the number of oxygen therapy patients who respond to our marketing campaigns, reduced the number of sales representatives hired, or impacted the timing of a pricing trial. Given these uncertainties, we have implemented cost savings by decreasing personnel hires, suspending our 401(k) match effective July 1, 2020, and reducing advertising spend, while also increasing rental setups to improve lead utilization. The health and safety of our people and their families continues to be our primary focus. Our ability to continue to operate without any significant negative operational impacts will in part depend on our ability to protect our employees and our supply chain. As the COVID-19 pandemic and related PHE has developed, we have taken numerous steps to help ensure the health and safety of our employees and their families. We follow recommended actions of government and health authorities to protect our employees, with particular measures in place for those working in our manufacturing facilities. Employees whose tasks can be done offsite have been allowed to work from home and most of our total personnel continue to work from home. We have also worked closely with local and national officials to keep our manufacturing facilities open due to the essential nature of our products. During 2020, we were able to broadly maintain our operations. We intend to continue to work with government authorities and implement our employee safety measures to help ensure that we are able to continue manufacturing and shipping our products during the COVID-19 pandemic and 66 related PHE. However, the COVID-19 pandemic and related PHE could result in an unforeseen disruption to our supply chain that could impact our operations. For additional information on risk factors that could impact our results, please refer to “Risk Factors” in Part I, Item 1A of this Annual Report on Form 10-K. Overview We are a medical technology company that primarily develops, manufactures and markets innovative POCs used to deliver supplemental long-term oxygen therapy to patients suffering from chronic respiratory conditions. Long-term oxygen therapy is defined as the provision of oxygen therapy for use at home in patients who have chronic low blood oxygen levels (hypoxemia). Traditionally, these patients have relied on stationary oxygen concentrator for use in the home and oxygen tanks or cylinders for mobile use, which we call the delivery model. The tanks and cylinders must be delivered regularly and have a finite amount of oxygen, which requires patients to plan activities outside of their homes around delivery schedules and a finite oxygen supply. Additionally, patients must attach long, cumbersome tubing to their stationary concentrators simply to enable mobility within their homes. Our proprietary Inogen One ® systems concentrate the air around the patient to offer a single source of supplemental oxygen anytime, anywhere with a portable device weighing as little as approximately 2.8 pounds with a single battery. Our Inogen One systems range from 2.6 to 6.5 hours of battery life with a single battery and can be plugged into an outlet when at home, in a car, or in a public place with outlets available. We believe our Inogen One systems reduce the patient’s reliance on stationary concentrators and scheduled deliveries of tanks with a finite supply of oxygen, thereby improving patient quality of life and fostering mobility. We believe that we were the first oxygen therapy manufacturer to employ a direct-to-consumer marketing strategy, meaning we advertise directly to patients, process their physician paperwork, and provide clinical support as needed, which we believe has contributed to our market leadership position in the POC market. While other manufacturers have also begun direct-to-consumer marketing campaigns to drive patient sales, we believe we are the only POC manufacturer that employs a direct-to-consumer rental strategy in the United States, meaning we bill Medicare or insurance on the consumer’s behalf. We derive the majority of our revenue from the sale and rental of our Inogen One systems and related accessories to patients, insurance carriers, home healthcare providers, resellers, charitable organizations, and distributors, including our private label partner. We sell multiple configurations of our Inogen One and Inogen At Home systems with various batteries, accessories, warranties, power cords and language settings. We also rent our products to Medicare beneficiaries and patients with other insurance coverage to support their long-term oxygen needs as prescribed by a physician as part of a care plan. Our goal is to design, build and market oxygen solutions that redefine how long-term oxygen therapy is delivered. To accomplish this goal and to grow our revenue, we intend to: • Expand our domestic direct-to-consumer sales and physician-based sales teams and increase productivity. During the year ended December 31, 2020, the number of inside sales representatives decreased to 300 from 329 as of December 31, 2019. In 2021, we plan to restart our sales capacity expansion efforts, selectively hiring new sales representatives across all three of our facilities. However, we expect fewer hires in the first half of 2021 due to the continued impacts of the COVID-19 pandemic and related PHE. Going forward, except as otherwise limited by the impact of the COVID-19 pandemic and related PHE, our plan is to continue to hire to expand sales capacity while focusing on increased productivity, improved sales personnel and lead distribution systems, and improved training. We also plan to expand our physician referral team to drive increased physician referrals for rental patients and direct-to-consumer sales. This specialized sales team consisted of 24 sales representatives and 5 support personnel as of December 31, 2020. We have seen and believe we could continue to see a decline in sales in our direct-to-consumer channel until patient mobility and consumer confidence increases after the COVID-19 pandemic and related PHE ends. As this is a dynamic situation, we plan to continue to monitor the COVID-19 PHE and may adjust our sales plans accordingly. • Expand our domestic direct-to-consumer marketing, drive better lead utilization, and optimize pricing. While we continued marketing efforts at a reduced level to continue to drive patient awareness of our products and patient inquiries about their ability to switch from their current oxygen products to our technology, media and advertising costs declined to $34.2 million in 2020 compared to $40.3 million in 2019, primarily associated with reductions due to the COVID-19 pandemic and related PHE and an increased focus on new rental setups. We plan to increase marketing spend to drive consumer and physician awareness of our products in 2021; however, during the COVID-19 pandemic and related PHE we expect to have lower marketing spend than in a typical year due to the lower return on those investments. We also plan to perform a pricing trial in 2021 to optimize pricing in our direct-to-consumer sales channel as well as look for opportunities to improve the close rate of leads through product offerings, pricing, and partnerships with HME providers, however, these may be delayed due to the COVID-19 pandemic and related PHE. As this is a dynamic situation, we plan 67 to continue to monitor the progression of the COVID-19 pandemic and related PHE in the United States and may adjust our marketing plan accordingly. • Expand our rental revenues through a dedicated rental intake team. During the year ended December 31, 2020, we expanded our rental intake team to focus exclusively on new rental additions to drive overall sales productivity and simplify training. We ended 2020 with 34 patient intake representatives and administrative personnel and plan to continue to scale the rental intake team in 2021, which we believe will lead to increased patients on service and growth in rental revenue in future periods. We also have increased focus on rentals from our direct-to-consumer inside and physician-based sales team, which should drive higher rental setups. Due to the COVID-19 PHE, Medicare and commercial payors have reduced some of the administrative burden for oxygen therapy, which also contributed to increased rental setups in the second, third and fourth quarters of 2020. We believe this change will continue to contribute to increased rental setups during the remainder of the COVID-19 pandemic and related PHE. We have also seen increased reimbursement rates in some areas for Medicare beneficiaries, which have increased rental revenue during the COVID-19 pandemic and related PHE and are expected to continue to do so for the remainder of the COVID-19 pandemic and related PHE. • Expand our domestic HME provider and reseller sales. We are also focused on building our domestic business-to-business partnerships, including relationships with distributors, key accounts, resellers, our private label partner, traditional HME providers, and charitable organizations. We offer patient-preferred, low service cost products and services to help providers convert their businesses to a non-delivery POC business model. While HME providers have been adopting our products over time, recent growth has been challenged due to difficulties in their ongoing efforts to restructure from the delivery business model to the non-delivery portable model, lack of access to available credit, provider capital expenditure constraints, and reimbursement rate changes. However, supplemental oxygen is a treatment prescribed by healthcare professionals for some patients with COVID-19. While there was an initial surge in demand for oxygen concentrators by our HME providers early in the COVID-19 pandemic and related PHE, domestic business-to-business demand declined in the second and third quarters of 2020 due to lower retail sales, lower patient travel, physician offices limiting patient interactions for COPD patient referrals, HME providers minimizing patient interactions in response to the COVID-19 pandemic and related PHE which includes replacing existing oxygen patient setups with POCs, and HME providers turning their purchasing focus to stationary oxygen concentrators to treat COVID-19 patients. Domestic HME provider demand increased in the fourth quarter of 2020, primarily due to increased demand for POCs as hospital systems and stationary oxygen concentrator supply were strained to keep up with the rapid increase in COVID-19 cases. • Increase international business-to-business adoption. Although our main growth opportunity remains POC adoption in the United States given what we still believe is a relatively low penetration rate, we believe there is a large international market opportunity. In order to take advantage of these international markets, we have built out an infrastructure over the past few years, which includes sales in 58 international countries and a contract manufacturing partner, Foxconn, located in the Czech Republic to support European sales volumes. As in the United States, while there was an initial surge in demand for oxygen concentrators by our international HME customers early in the COVID-19 pandemic, international demand declined in the second, third and fourth quarters of 2020 primarily due to the temporary closures and reduced operating capacity of certain European respiratory assessment centers due to the COVID-19 pandemic, continued tender delays in certain European markets, and decreased sales in other markets, primarily Canada. In addition, as in the United States, providers turned their focus to supplying stationary oxygen concentrators with higher flow characteristics in response to the COVID-19 pandemic. To grow our international sales markets, we are also in the process of developing regulatory and sales pathways to capture opportunities in new and emerging markets. We expect to begin sales in the Chinese market as early as the end of 2021 although this could be delayed due to regulatory clearance delays, other impacts of the COVID-19 pandemic or government actions, by the United States or China that impose barriers or restrictions that would impact our ability to access the Chinese market. Over time, as the U.S. and European markets mature, our growth will depend on our ability to drive POC adoption in emerging markets, where limited oxygen therapy treatment exists today. However, growth may also be limited by currency fluctuations, capital expenditure constraints, ongoing restructuring challenges, and tender uncertainty. • Invest in our oxygen product offerings to develop innovative products . We incurred $14.1 million, $9.4 million and $7.0 million in 2020, 2019 and 2018, respectively, in research and development expenses, and we intend to continue to make such investments in the foreseeable future. We launched our fifth-generation POC, the Inogen One G5, in our direct-to-consumer channel in 2019. Some international markets require additional regulatory or reimbursement clearances to release the product, and we are in the process of obtaining additional clearances to access additional markets. The Inogen One G5 weighs 4.7 pounds and produces 1,260 ml per minute of oxygen output, with very quiet operation at 38 dBA and our longest battery life at 6.5 hours for a single battery and up to 13 hours for a double battery. We estimate that the Inogen One G5 is suitable for over 90% of ambulatory long-term oxygen therapy patients based on our analysis of the patients who have contacted us and their clinical needs. We expect the Inogen One G5 to obsolete the Inogen One G3 ® 68 over the short- term. Manufacturing cost for our Inogen One G5 was at parity with our Inogen One G3 starting in the third quarter of 2020, and we still expect the Inogen One G5 to be our lowest cost to manufacture over time. The Inogen One G5 represented more than 6 9 % of total domestic POC units sold in 2020, showing the strong demand for this product from both patients and providers. Inogen Connect, our connectivity platform on our Inogen One G4 ® and Inogen One G5 products in the United States and Canada is compatible with Apple and Android platforms and includes patient features such as purity status, battery life, product support functions, notification alerts, and remote software updates. We believe home oxygen providers will also find features such as remote troubleshooting, equipment health checks, and location tracking to help drive operational efficiencies when transitioning away from the oxygen tank delivery model. • Expand our product offerings. In August 2019, we acquired New Aera. New Aera’s patented and FDA-cleared Tidal Assist ® Ventilator (TAV ® ) system is designed to deliver increased air flow and pressure from an approximately 4-ounce pocket-size unit, features a state-of-the-art nasal pillow interface, and is compatible with certain oxygen concentrators, oxygen cylinders, wall gas, and certain medical air sources. TAV therapy with oxygen has been clinically demonstrated during periods of exercise to reduce breathlessness, increase exercise endurance, and improve oxygen saturation for patients suffering from certain chronic lung disease compared to oxygen therapy alone. We began a limited launch of the TAV product in December 2019 in our domestic direct-to-consumer channel and in our domestic business-to-business channel. We plan to only sell this product across our domestic direct-to-consumer channel and in our domestic business-to-business channel in 2021, although we expect limited contributions to revenue in 2021. The COVID-19 pandemic and related PHE also had an impact on sales of this product in the second, third and fourth quarters of 2020, primarily due to lower retail demand. We plan to incorporate the TAV technology directly into our Inogen One POCs and make the TAV product compatible with our Inogen At Home stationary concentrators to continue to advance patient preference and maintain our technology leadership position in the long-term oxygen therapy market. In addition, we plan to use this technology as a platform to expand our total addressable market into the high-growth non-invasive ventilation (NIV) market, where we believe there is a significant worldwide untreated market opportunity. We believe this market could undergo disruption similar to oxygen given the immobile nature of legacy NIV product offerings. The monthly Medicare reimbursement rate is significantly higher for NIV products than oxygen therapy at a minimum of $934 a month. Also, effective January 1, 2019, a new Medicare HCPCS code has been added to allow billing for a multi-function ventilator that includes both ventilation and oxygen. It is uncertain if the TAV product acquired from New Aera will be reimbursable in its current configuration under HCPCS code E0466. We requested confirmation on the assigned HCPCS codes for the TAV system from the Pricing, Data Analysis, and Coding (PDAC) Contractor in August 2019 following the closing of the New Aera transaction. In August 2019, we received positive confirmation that this product was assigned HCPCS code E0466. However, in September 2019, we received a revised communication that the product was assigned HCPCS code E1390 and E1352, which was then revoked at our request in December 2019. In September 2019, we appealed to CMS, and in January 2020 our appeal was denied. On September 21, 2020, we filed a lawsuit against defendants, Alex M. Azar, Secretary of the Department of Health and Human Services (HHS), in his official capacity, Seema Verma, Administrator of the Centers for Medicare and Medicaid Services (CMS), in her official capacity and Palmetto GBA, LLC. The lawsuit seeks to invalidate the defendants’ arbitrary and capricious decision to retract a valid HCPCS code to our TAV, thereby eliminating reimbursements for the ventilator, in violation of the Administrative Procedures Act. Further, CMS’s failure to provide notice and the opportunity to comment on a change in HCPCS code verification for the Sidekick TAV and similar devices constitutes a violation of the procedural right provided under the Social Security Act, and our due process rights. If we do not receive revised coding, it could limit this product’s adoption by HME providers and also our direct rentals until revisions are made to the product to meet the coding requirements. In addition, the Medicare Coverage Advisory Committee (MEDCAC) had a meeting on July 22, 2020 to discuss home use of non-invasive positive pressure ventilation in patients with chronic respiratory failure consequent to COPD. CMS is seeking MEDCAC’s recommendations regarding the characteristics that define those patient selection and usage criteria. This request could signal forthcoming changes in Medicare coverage of these items, and possibly changes in HCPCS codes, which could impact our NIV business and growth initiatives. For a discussion of certain significant risks relating to the TAV reimbursement, see the risk factor entitled “ The competitive bidding process or other reimbursement policy changes under Medicare or other third-party payors could negatively affect our business and financial condition .” We have been developing and refining the manufacturing of our Inogen One systems since 2004. While nearly all of our manufacturing and assembly processes were originally outsourced, assembly of the compressors, sieve beds, concentrators and certain manifolds were brought in-house in order to improve quality control and reduce cost. In support of our European sales, we use a contract manufacturer located in the Czech Republic to manufacture high volume products and perform product repairs to improve delivery to our European accounts. We expect to maintain our assembly operations for our products at our facilities in Texas and California. In 2020, we focused on reducing the cost of our Inogen One G5 product, expanding manufacturing of the TAV product and 69 increasing the robustness of our supply chain to reduce potential component constraints as we grow our business , and expect to continue this focus in 202 1 . We also use lean manufacturing practices to maximize manufacturing efficiency. We rely on third-party manufacturers to supply several components of our products. We typically enter into master service agreements for these components that specify quantity and quality requirements and delivery terms. In certain cases, these agreements can be terminated by either party upon relatively short notice. We have elected to source certain key components from single sources of supply, including our batteries, motors, valves, TAV-compatible stationary concentrators, columns, and some molded plastic components. We believe that maintaining a single source of supply allows us to control production costs and inventory levels and to manage component quality. In order to mitigate against the risks related to a single source of supply, for certain components we qualify alternative suppliers and develop contingency plans for responding to disruptions. However, any reduction or halt in supply from one of these single-source suppliers could limit our ability to manufacture our products or devices until a replacement supplier is found and qualified. For additional discussion of potential risks related to our manufacturing and raw materials, please see the risk factor entitled “ We obtain some of the components, subassemblies and completed products included in our products from a single source or a limited group of manufacturers or suppliers, and the partial or complete loss of one or more of these manufacturers or suppliers could cause significant production delays, an inability to meet customer demand, substantial loss in revenue, and an adverse effect on our financial condition and results of operations. ” Historically, we have generated a majority of our revenue from sales and rentals to customers in the United States. In the years ended December 31, 2020, 2019 and 2018, approximately 20.1%, 21.5% and 21.6%, respectively, of our total revenue was from sales to customers outside the United States, primarily in Europe. Approximately 73.6%, 70.2% and 74.8% of the non-U.S. revenue for the years ended December 31, 2020, 2019 and 2018, respectively, was invoiced in Euros with the remainder invoiced in United States dollars. We sell our products in 58 countries outside the United States through our wholly-owned subsidiary, distributors or directly to large “house” accounts, which include gas companies, HME oxygen providers, and resellers. In those instances, we sell to and bill the distributor or “house” accounts directly, leaving responsibility for the patient billing, support and clinical setup to the local provider. Our total revenue was $308.5 million, $361.9 million and $358.1 million for the years ended December 31, 2020, 2019 and 2018, respectively. The decrease in total revenue in the year ended December 31, 2020 compared to the prior year was primarily due to a decline in direct-to-consumer sales and domestic and international business-to-business sales, primarily associated with the COVID-19 pandemic and related PHE, partially offset by an increase in rental revenue. We generated net income (loss) of $(5.8) million, $21.0 million and $51.8 million in the years ended December 31, 2020, 2019 and 2018, respectively. We generated Adjusted EBITDA of $21.6 million, $43.3 million and $61.3 million in the years ended December 31, 2020, 2019 and 2018, respectively (see “Non-GAAP financial measures” for reconciliations between U.S. GAAP and non-GAAP results). As of December 31, 2020, our retained earnings were $75.6 million. Sales revenue Our future financial performance will be driven in part by the growth in sales of our Inogen One systems, and, to a lesser extent, sales of batteries, other accessories, our Inogen At Home stationary oxygen concentrators and our TAV products. We plan to grow our system sales in the coming years through multiple strategies including: hiring additional sales representatives, improving productivity, investing in consumer and physician awareness through increased sales and marketing efforts, expanding our sales infrastructure and efforts outside of the United States, expanding our business-to-business sales through key partnerships, and enhancing our product offerings through additional product launches, although, as mentioned above, these plans have been and may continue to be impacted by the COVID-19 pandemic and related PHE. While we believe most HME providers are still in the process of converting their business model to a non-delivery model and purchase POCs, growth has been challenged and we expect it could continue to be challenged due to the COVID-19 pandemic and related PHE, their ongoing restructuring efforts, lack of access to available credit, provider capital expenditure constraints, and potential changes in reimbursement rates. As our product offerings grow, we solicit feedback from our customers and focus our research and development efforts on continuing to improve patient preference and reduce the total cost of the product in order to further drive sales of our products. Our direct-to-consumer sales process involves numerous interactions with the individual patient, their physician and the physician’s staff, and includes an in-depth analysis and review of our product, the patient’s diagnosis and prescribed oxygen or NIV therapy, including procuring an oxygen prescription, although, as discussed above, this process has been disrupted due to the COVID-19 pandemic and related PHE and we expect that such disruption will continue for the duration of the COVID-19 pandemic and related PHE. The patient may consider whether to finance the product through an Inogen-approved third party or purchase the equipment. Product is not deployed until both the prescription and payment are received. Once a full system is deployed, the patient has 30 calendar days to return the product, subject to the payment of a minimal processing and handling fee. Approximately 6-9% of consumers who purchase a system return the system during this 30-day return period. 70 Our business-to-business efforts are focused on selling to distributors, HME oxygen and NIV providers, our private label partner, resellers, and charitable organizations who are based inside and outside of the United States. This process involves interactions with various key customer stakeholders including sales, purchasing, product testing, and clinical personnel. Businesses that have patient demand that can be met with our products place purchase orders to secure product deployment. This may be influenced based on outside factors, including the result of tender offerings, changes in insurance plan coverage or reimbursement rates, business restructuring activities toward a non-delivery model, capital constraints, and overall changes in the net oxygen and NIV therapy patient populations, and is presently being impacted by the COVID-19 pandemic and related PHE. Products are shipped freight on board (FOB) Inogen dock domestically, and based on financial history and profile, businesses may either prepay or receive extended payment terms. Products are shipped both FOB Inogen dock and Delivery Duty Paid (DDP) for certain international shipments depending on the shipper used. DDP shipments are Inogen’s property until title has transferred which is upon duty being paid and delivered to the customer. As a result of these factors, product purchases can be subject to changes in demand by customers. We sold approximately 178,900 systems in 2020, 201,100 systems in 2019 and 198,600 systems in 2018. Management focuses on system sales as an indicator of current business success. Rental revenue Our direct-to-consumer rental process involves numerous interactions with the individual patient, their physician and the physician’s staff. The process includes an in-depth analysis and review of our product, the patient’s diagnosis and prescribed oxygen or NIV therapy, and their medical history to confirm the appropriateness of our product for the patient’s oxygen therapy or NIV therapy and compliance with Medicare and private payor billing requirements, which often necessitates additional physician evaluation and/or testing as well as a Certificate of Medical Necessity for oxygen. Once the product is deployed, the patient receives instruction on product use and may receive a clinical titration from our licensed staff to confirm the product meets the patient’s medical oxygen needs prior to billing. As a result, the period of time from initial contact with a patient to billing can vary significantly and be up to one month or longer. However, due to the COVID-19 PHE, CMS has reduced the paperwork requirements for Medicare oxygen therapy patients, as discussed in more detail in the Reimbursement section below, effective in early March 2020. Rental revenue increased in 2020 compared to 2019, primarily due to a greater number of patients on service, higher Medicare reimbursement rates, higher billable patients as a percent of total patients on service, and lower rental revenue adjustments. Medicare reimbursement rates for oxygen therapy increased 1.5% to 3.5%, effective January 1, 2020. In addition, as part of the CARES Act (discussed in more detail in the Reimbursement section below), the 2% Medicare sequestration reduction was temporarily eliminated, and Medicare reimbursement rates for non-rural, non-competitive bid areas through the duration of the COVID-19 PHE were increased to a 75/25 blended rate retroactive to March 6, 2020. The 50/50 blended rate for HME providers in rural and non-contiguous, non-competitive bid areas was also extended for the duration of the COVID-19 PHE, which could increase the rates in 2021 if the COVID-19 PHE continues. We plan to add new rental patients on service in future periods through multiple strategies, including expanding our rental intake team and physician-based sales teams, expanding our direct-to-consumer marketing efforts, investing in patient and physician awareness, and securing additional insurance contracts. A portion of rentals include a capped rental period during which no additional reimbursement is allowed unless additional criteria are met. In this scenario, the ratio of billable patients to total patients on service is critical to maintaining rental revenue growth as patients on service increases. Medicare has noted a certain percentage of beneficiaries, approximately 25%, based on their review of Medicare claims, reach the 36 th month of eligible reimbursement and enter the capped rental period. The percentage of capped patients may fluctuate over time as new patients come on service, patients come off of service before and during the capped rental period, and existing patients enter the capped rental period. We had approximately 32,200, 25,300 and 26,900 oxygen rental patients as of December 31, 2020, 2019 and 2018, respectively. Management focuses on patients on service as a leading indicator of likely future rental revenue; however, actual rental revenue recognized is subject to a variety of other factors, including reimbursement levels by payor, patient location, the number of capped patients, write-offs for uncollectable balances, and rental revenue adjustments. Reimbursement We rely significantly on reimbursement from Medicare and private payors, including Medicare Advantage plans, Medicaid and patients for our rental revenue. A discussion of third-party reimbursement is contained in Item 1, Third-party reimbursement in this Annual Report on Form 10-K. For the years ended December 31, 2020, 2019 and 2018, approximately 81.5%, 81.1% and 78.0%, respectively, of our rental revenue was derived from Medicare’s traditional fee-for-service reimbursement programs. The U.S. list price for our stationary oxygen rentals (HCPCS E1390) is $260 per month and the U.S. list price for our oxygen generating portable equipment (OGPE) rentals (HCPCS E1392) is $70 per month. 71 Basis of presentation The following describes the line items set forth in our consolidated statements of comprehensive income (loss). Revenue We classify our revenue in two main categories: sales revenue and rental revenue. There will be fluctuations in mix between business-to-business sales, direct-to-consumer sales and rental revenue from period-to-period. Product selling prices and gross margins may fluctuate as we introduce new products, reduce our product costs, have changes in purchase volumes, and as currency variations occur. For example, the gross margin for our Inogen One G4 system is higher than our Inogen One G3 system due to lower manufacturing costs and similar average selling prices. Thus, to the extent our sales of our Inogen One G4 systems are higher than sales of our Inogen One G3 systems, our overall gross margins should improve and, conversely, to the extent our sales of our Inogen One G3 systems are higher than sales of our Inogen One G4 systems, our overall gross margins should decline. Quarter-over-quarter results may vary due to seasonality in both the international and domestic markets, as discussed in Item 1. Seasonality and elsewhere in this Annual Report on Form 10-K. Sales revenue Our sales revenue is primarily derived from the sale of our Inogen One systems, Inogen At Home systems, TAV systems, and related accessories to individual consumers, our private label partner, HME providers, distributors, resellers, and charitable organizations worldwide. Sales revenue is classified into two areas: business-to-business sales and direct-to-consumer sales. Generally, our direct-to-consumer sales have higher gross margins than our business-to-business sales. Rental revenue Our rental revenue is primarily derived from the rental of our Inogen One and Inogen At Home systems to patients through reimbursement from Medicare, private payors and Medicaid, which typically also includes a patient responsibility component for patient co-insurance and deductibles. Rental revenue increased in 2020, primarily due to higher patients on service, higher billable patients as a percent of total patients on service, higher Medicare reimbursement rates, and lower revenue adjustments. We expect our rental revenue to increase in future periods as we scale the rental intake and sales teams and increase new rental setups. In addition, for the duration of the COVID-19 PHE, we expect to benefit from higher Medicare reimbursement rates for oxygen therapy enacted due to the COVID-19 PHE. We also expect that our rental revenue will be impacted by the number of our sales and rental intake representatives, reimbursement rate changes, including the impact of COVID-19 PHE changes, the level of and response from potential customers to direct-to-consumer marketing spend, product launches, the number of billable patients and denial rates, and other uncontrollable factors such as changes in the market and competition. Cost of revenue Cost of sales revenue Cost of sales revenue consists primarily of costs incurred in the production process, including component materials, assembly labor and overhead, warranty expense, provisions for slow-moving and obsolete inventory, rework and delivery costs for items sold. Labor and overhead expenses consist primarily of personnel-related expenses, including wages, bonuses, benefits, and stock-based compensation for manufacturing, logistics, repair, manufacturing engineering, and quality assurance employees and temporary labor. Cost of sales revenue also includes manufacturing freight in, depreciation expense, facilities costs and materials. Provisions for warranty obligations are included in cost of sales revenue and are provided for at the time of revenue recognition. We continue to make progress towards reducing the average unit costs of our products as a result of our ongoing efforts to develop lower-cost systems, negotiate with our suppliers, improve our manufacturing processes, and increase production volume and yields. At the same time, recent United States policies related to global trade and tariffs may also increase our average unit cost. The current economic environment has introduced greater uncertainty with respect to potential trade regulations, including changes to United States policies related to global trade and tariffs. We continue to monitor the Section 301 tariffs being imposed by the United States on certain imported Chinese materials and products in addition to potential retaliatory responses from other nations. In 2020 and 2019, the impact of the China tariffs on our financial results was minimal as we have received some exemptions, negotiated cost sharing and price reductions with suppliers, and re-allocated purchases. Assuming the Chinese tariffs stay at the current levels, we currently expect the overall financial impact to our business to be minimal to the average unit cost for 2021. 72 We expect the TAV system to have a higher sales gross margin than our existing oxygen therapy products . For these reasons, we expect sales gross margin percentage to fluctuate over time based on the sales channel mix, product mix, and changes in average selling prices and cost per unit. Cost of rental revenue Cost of rental revenue consists primarily of depreciation expense; service costs for rental patients, including rework costs, material, labor, freight, and consumable disposables; and logistics costs. We expect rental gross margin percentage to increase over time, primarily associated with higher rental revenue per patient on service and lower costs per patient on service. We expect the average cost of rental revenue per patient on service to decline in future periods as a result of our ongoing efforts to reduce average unit cost of our systems as well as reductions in depreciation, service costs, and logistics costs. Operating expense Research and development Our research and development expense consists primarily of personnel-related expenses, including wages, bonuses, benefits and stock-based compensation for research and development and engineering employees, facility costs, laboratory supplies, product development materials, consulting fees and related costs, clinical study costs, and testing costs for new product launches as well as enhancements to existing products. We have made substantial investments in research and development since our inception. Our research and development efforts have focused primarily on the tasks required to enhance our technologies and to support development and commercialization of new and existing products. Beginning in the third quarter of 2019, research and development expense also includes intangible amortization costs associated with the New Aera acquisition, which is expected to substantially increase our research and development expense in 2021 through 2028 by approximately $7.8 million per year and $4.9 million in 2029. We plan to continue to invest in research and development activities to stay at the forefront of patient preference in oxygen therapy and NIV devices. We expect research and development expense to increase in absolute dollars in future periods as we continue to invest in our engineering and technology teams to support our new and enhanced product research and development efforts and manufacturing improvements. We expect increased research and development costs associated with the New Aera acquisition to incorporate the TAV technology into our oxygen concentrator and new non-invasive ventilator product portfolios as well as intangible amortization costs. Sales and marketing Our sales and marketing expense primarily supports our direct-to-consumer sales and rental strategy and consists mainly of personnel-related expenses, including wages, bonuses, commissions, benefits, and stock-based compensation for sales, marketing, customer service, rental intake, and clinical service employees. It also includes expenses for media and advertising, printing, informational kits, dues and fees, credit card fees, recruiting, training, sales promotional activities, travel and entertainment expenses as well as allocated facilities costs. Sales and marketing expense decreased in 2020 compared to 2019, primarily associated with lower advertising expense. Our average direct-to-consumer sales representative headcount in 2020 was down sequentially from 2019 as attrition outpaced hiring in the period. We expect minimal direct-to-consumer sales representative hiring in the first half of 2021 due to the COVID-19 pandemic and related PHE, and plan to focus on sales representative efficiencies, including improved sales representative productivity and lead utilization, while we continue to monitor the impact of the COVID-19 pandemic and related PHE. Due to the COVID-19 pandemic and related PHE, we have also reduced and expect to continue to reduce marketing spend. However, we still expect an increase in sales and marketing expense in future periods as we continue to invest in our business, including expanding our sales and sales support team including our physician-based sales team, increasing our rental infrastructure, increasing media spend to drive consumer awareness, and rising patient support costs as our patient and customer base increases. We also expect increased sales and marketing costs in 2021 associated with the expanded launch of the TAV product following the limited launch in 2020. General and administrative Our general and administrative expense consists primarily of personnel-related expenses, including wages, bonuses, benefits, and stock-based compensation for employees in our compliance, finance, medical billing, order intake, human resources, and information technology (IT) departments as well as facilities costs, sales bad debt expense, and board of directors’ expenses, including 73 stock-based compensation. In addition, general and administrative expense includes professional services, such as legal, patent registration and defense costs, insurance, consulting and accounting services, including audit and tax services, and travel and entertainment expenses. We expect general and administrative expense to increase in future periods as the number of administrative personnel grows and we continue to introduce new products, broaden our customer base and grow our business. We expect general and administrative expense to increase in absolute dollars as we continue to invest in corporate infrastructure to support our growth including personnel-related expenses, professional services fees and compliance costs associated with operating as a public company. Those costs include increases in our accounting, medical billing, human resources, and IT personnel, as well as increases in additional consulting, legal and accounting fees, facilities costs, insurance costs, and board of directors’ compensation. Other income (expense), net Our other income (expense), net consists primarily of interest income earned on cash equivalents and marketable securities as well as foreign currency gains and (losses). Income taxes We account for income taxes in accordance with Accounting Standards Codification (ASC) 740— Income Taxes . Under ASC 740, income taxes are recognized for the amount of taxes payable or refundable for the current period and deferred tax liabilities and assets are recognized for the future tax consequences of transactions that have been recognized in our consolidated financial statements or tax returns. A valuation allowance is provided when it is more likely than not that some portion, or all, of the deferred tax asset will not be realized. We account for uncertainties in income tax in accordance with ASC 740-10— Accounting for Uncertainty in Income Taxes . ASC 740-10 prescribes a recognition threshold and measurement attribute for the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. This accounting standard also provides guidance on derecognition, classification, interest and penalties, accounting in interim periods, disclosure and transition. The accounting for stock-based compensation will increase or decrease our effective tax rate based upon the difference between our stock-based compensation expense and the deductions taken on our U.S. tax return, which depends upon the stock price at the time of employee option exercise or award vesting. We recognize excess tax benefits or deficiencies on a discrete basis, and we anticipate our effective tax rate will vary from year-to-year depending on our stock price in each period. Results of operations Comparison of years ended December 31, 2020 and 2019 Revenue Years ended December 31, Change 2020 vs. 2019 % of Revenue (amounts in thousands) 2020 2019 $ % 2020 2019 Sales revenue $ 280,189 $ 340,546 $ (60,357 ) -17.7 % 90.8 % 94.1 % Rental revenue 28,298 21,397 6,901 32.3 % 9.2 % 5.9 % Total revenue $ 308,487 $ 361,943 $ (53,456 ) -14.8 % 100.0 % 100.0 % Sales revenue decreased $60.4 million for the year ended December 31, 2020 from the year ended December 31, 2019, or a decrease of 17.7% from the comparable year. The decrease was primarily attributable to reduced direct-to-consumer sales and reduced domestic and international business-to-business sales, primarily due to the impact of the COVID-19 pandemic and related PHE and Inogen One G5 supply constraints in the first quarter of 2020. We sold approximately 178,900 oxygen systems during the year ended December 31, 2020 compared to approximately 201,100 oxygen systems sold during the year ended December 31, 2019, or a decrease of 11.0%. The decrease in the number of systems sold resulted mainly from a decrease in sales across all channels primarily due to the COVID-19 pandemic and related PHE and the Inogen One G5 supply constraints in the first quarter of 2020. Rental revenue increased $6.9 million for the year ended December 31, 2020 from the year ended December 31, 2019, or an increase of 32.3% from the comparable year. The increase in rental revenue was primarily related to higher rental patients on service, higher billable patients as a percent of total patients on service, higher Medicare reimbursement rates, and lower rental revenue adjustments. 74 (amounts in thousands) Years ended December 31, Change 2020 vs. 2019 % of Revenue Revenue by region and category 2020 2019 $ % 2020 2019 Business-to-business domestic sales $ 96,423 $ 106,428 $ (10,005 ) -9.4 % 31.3 % 29.4 % Business-to-business international sales 62,147 77,960 (15,813 ) -20.3 % 20.1 % 21.5 % Direct-to-consumer domestic sales 121,619 156,158 (34,539 ) -22.1 % 39.4 % 43.2 % Direct-to-consumer domestic rentals 28,298 21,397 6,901 32.3 % 9.2 % 5.9 % Total revenue $ 308,487 $ 361,943 $ (53,456 ) -14.8 % 100.0 % 100.0 % Domestic business-to-business sales decreased 9.4% for the year ended December 31, 2020 compared to the year ended December 31, 2019. The decrease was primarily due to decreased demand from our HME partners for oxygen concentrators in response to the COVID-19 pandemic and related PHE due to lower retail sales, lower patient travel, physician offices limiting patient interactions that traditionally have led to new oxygen patient referrals, HME providers minimizing patient interactions in response to the COVID-19 pandemic and related PHE which includes replacing existing oxygen patient setups with POCs, and HME providers turning their purchasing focus to stationary oxygen concentrators to treat COVID-19 patients. In addition, lower Inogen One G5 availability early in the year and uncertainty around competitive bidding Round 2021 for most of 2020 contributed to lower sales in the year. International business-to-business sales decreased 20.3% for the year ended December 31, 2020 compared to the year ended December 31, 2019, mostly driven by the temporary closures and reduced operating capacity of certain European respiratory assessment centers due to the COVID-19 pandemic and continued tender delays in certain European markets. In addition, like in the United States, HME providers turned their focus to supplying stationary oxygen concentrators with higher flow characteristics in responses to the COVID-19 pandemic. In the year ended December 31, 2020, sales in Europe as a percentage of total international sales revenue decreased slightly to 85.8% versus 86.4% in the comparative period in 2019. Domestic direct-to-consumer sales decreased 22.1% for the year ended December 31, 2020 compared to the year ended December 31, 2019, primarily due to the impact of the COVID-19 pandemic and related PHE on reduced consumer travel and mobility as well as lower consumer confidence, which decreased demand and associated sales representative productivity in the period compared to the same period in the prior year. In addition, sales declined associated with an approximate 4% decline in average direct-to-consumer sales representative headcount in the comparative periods. Domestic direct-to-consumer rentals increased 32.3% for the year ended December 31, 2020 compared to the year ended December 31, 2019, primarily due to an increase in patients on service, higher billable patients as a percent of total patients on service, increased Medicare reimbursement rates, and lower rental revenue adjustments. Cost of revenue and gross profit Years ended December 31, Change 2020 vs. 2019 % of Revenue (amounts in thousands) 2020 2019 $ % 2020 2019 Cost of sales revenue $ 156,764 $ 175,974 $ (19,210 ) -10.9 % 50.8 % 48.6 % Cost of rental revenue 13,543 14,108 (565 ) -4.0 % 4.5 % 3.9 % Total cost of revenue $ 170,307 $ 190,082 $ (19,775 ) -10.4 % 55.2 % 52.5 % Gross profit - sales revenue $ 123,425 $ 164,572 $ (41,147 ) -25.0 % 40.0 % 45.5 % Gross profit - rental revenue 14,755 7,289 7,466 102.4 % 4.8 % 2.0 % Total gross profit $ 138,180 $ 171,861 $ (33,681 ) -19.6 % 44.8 % 47.5 % Gross margin percentage - sales revenue 44.1 % 48.3 % Gross margin percentage - rental revenue 52.1 % 34.1 % Total gross margin percentage 44.8 % 47.5 % 75 Cost of sales revenue decreased $19.2 million for the year ended December 31, 2020 from the year ended December 31, 2019, or a decrease of 10.9% from the comparable year. The decrease in cost of sales revenue was primarily attributable to lower sales and related bill of material costs, partially offset by higher material and overhead cost per unit. Cost of rental revenue decreased $0.6 million for the year ended December 31, 2020 from the year ended December 31, 2019, or a decrease of 4.0% from the comparable year. The decrease in cost of rental revenue was primarily attributable to reduced rental asset depreciation expense and servicing costs. Cost of rental revenue included $5.7 million of rental asset depreciation for the year ended December 31, 2020 compared to $6.3 million for the year ended December 31, 2019. Sales revenue gross margin percentage decreased to 44.1% for the year ended December 31, 2020 from 48.3% for the year ended December 31, 2019. The decrease was primarily related to lower average selling prices, increased domestic business-to-business sales mix which has a lower gross margin, and higher cost of goods sold associated with certain manufacturing inefficiencies in the period that contributed to higher material and labor and overhead costs per unit. Total worldwide business-to-business sales revenue accounted for 56.6% of total sales revenue in the year ended December 31, 2020 versus 54.1% in the year ended December 31, 2019. Rental revenue gross margin percentage increased to 52.1% for the year ended December 31, 2020 from 34.1% for the year ended December 31, 2019, primarily due to higher Medicare reimbursement rates, higher billable patients as a percent of total patients on service, lower revenue adjustments and lower depreciation and servicing costs per patient on service. Research and development expense Years ended December 31, Change 2020 vs. 2019 % of Revenue (amounts in thousands) 2020 2019 $ % 2020 2019 Research and development expense $ 14,080 $ 9,401 $ 4,679 49.8 % 4.6 % 2.6 % Research and development expense increased $4.7 million for the year ended December 31, 2020 from the year ended December 31, 2019, or an increase of 49.8% over the comparable period, primarily due to $4.9 million in intangible amortization costs primarily related to the New Aera acquisition, partially offset by a $0.4 million decrease in product development expenses. Sales and marketing expense Years ended December 31, Change 2020 vs. 2019 % of Revenue (amounts in thousands) 2020 2019 $ % 2020 2019 Sales and marketing expense $ 97,520 $ 105,550 $ (8,030 ) -7.6 % 31.6 % 29.2 % Sales and marketing expense decreased $8.0 million for the year ended December 31, 2020 from the year ended December 31, 2019, or a decrease of 7.6% from the comparable period, primarily attributable to decreases of $6.1 million of advertising costs, $0.8 million of personnel-related expenses mainly associated with lower commissions and customer service expense, $0.8 million of credit card fees, $0.7 million in incentives and giveaways, and $0.5 million of travel and entertainment expenses, partially offset by an increase of $0.7 million in dues, fees, and license costs and $0.4 million in facilities costs. In the year ended December 31, 2020, we spent $34.2 million in media and advertising costs versus $40.3 million in the comparative period in 2019. General and administrative expense Years ended December 31, Change 2020 vs. 2019 % of Revenue (amounts in thousands) 2020 2019 $ % 2020 2019 General and administrative expense $ 38,605 $ 37,121 $ 1,484 4.0 % 12.5 % 10.2 % General and administrative expense increased $1.5 million for the year ended December 31, 2020 from the year ended December 31, 2019, or an increase of 4.0% from the comparable period. The increase was primarily attributable to $1.4 million in consulting fees, $0.4 million in facilities costs, $0.4 million in personnel-related expenses, and $0.4 million in directors and officers insurance costs, partially offset by $1.1 million in lower legal fees and $0.9 million reimbursement from the CARES Act Provider Relief Fund from the COVID-19 pandemic and related PHE. 76 Other income (expense) Years ended December 31, Change 2020 vs. 2019 % of Revenue (amounts in thousands) 2020 2019 $ % 2020 2019 Interest income $ 909 $ 4,712 $ (3,803 ) -80.7 % 0.3 % 1.3 % Other income (expense) 5,836 (229 ) 6,065 2648.5 % 1.9 % -0.1 % Total other income, net $ 6,745 $ 4,483 $ 2,262 50.5 % 2.2 % 1.2 % Total other income, net increased $2.3 million for the year ended December 31, 2020 from the year ended December 31, 2019, or an increase of 50.5% from the comparable period. The increase was primarily attributable to $5.3 million in other income from the CARES Act Provider Relief Fund due to lost revenues from the COVID-19 pandemic and related PHE and a $0.7 million increase in net foreign currency gains, partially offset by a decrease of $3.8 million in interest income on marketable securities due to the lower interest rate environment and lower invested balances in marketable securities in 2020 compared to 2019. Income tax expense Years ended December 31, Change 2020 vs. 2019 % of Revenue (amounts in thousands) 2020 2019 $ % 2020 2019 Income tax expense $ 549 $ 3,322 $ (2,773 ) -83.5 % 0.2 % 0.9 % Effective income tax rate -10.4 % 13.7 % Income tax expense decreased $2.8 million for the year ended December 31, 2020 from the year ended December 31, 2019, primarily resulting from a decrease in income before income tax expense, partially offset by the change in net tax expense (benefit) for research and development credits and the change in the shortfall related to stock-based compensation expense. Our effective tax rate in the year ended December 31, 2020 decreased compared to the year ended December 31, 2019, primarily due to the increase in excess tax deficiencies recognized from stock-based compensation and state income taxes. Net income (loss) Years ended December 31, Change 2020 vs. 2019 % of Revenue (amounts in thousands) 2020 2019 $ % 2020 2019 Net income (loss) $ (5,829 ) $ 20,950 $ (26,779 ) -127.8 % -1.9 % 5.8 % Net income (loss) decreased $26.8 million for the year ended December 31, 2020 from the year ended December 31, 2019, or a decrease of 127.8% from the comparable period. The decrease in net income (loss) was primarily related to lower sales revenue and gross margin, partially offset by lower operating expenses and other income from the CARES Act Provider Relief Fund. Seasonality We believe our sales may be impacted by seasonal factors. For example, we typically experience higher total sales in the second and third quarters, as a result of consumers traveling and vacationing during warmer weather in the spring and summer months, but this may vary year-over-year. In particular, due to the COVID-19 pandemic and related PHE, we have seen and expect to continue to see a disruption in our normal seasonal trends, as, due to the mandates and behaviors emanating from the COVID-19 pandemic and related PHE, including shelter-in-place orders, reduced travel, and lower consumer confidence, we did not see the typical seasonal increases in direct-to-consumer sales in 2020 that we have seen in prior years. As more HME providers adopt portable oxygen concentrators in their businesses, we expect that this could change our historical seasonality in the domestic business-to-business channel, which was previously influenced mainly by consumer buying patterns. Direct-to-consumer sales seasonality may also be impacted by the number of sales representatives and the amount of marketing spend in each quarter. 77 The following tables set forth our unaudited quarterly consolidated statements of comprehensive income (loss) data for each of the eight quarters in the period ended December 31, 20 20 . We have prepared the quarterly statements of income data on a basis consistent with the audited consolidated financial statements included in Part II, Item 8, "Financial Statements and Supplementary Data" in this Annual Report on Form 10-K. In the opinion of management, the financial information reflects all adjustments, consisting only of normal recurring adjustments, which we consider necessary for a fair presentation of this data. This information should be read in conjunction with the audited consolidated financial statements and related notes included in Part II, Item 8, "Financial Statements and Supplementary Data" in this Annual Report on Form 10-K. The results of historical periods are not necessarily indicative of the results of operations for any future period. (amounts in thousands, except share and per share amounts) Quarterly Results 2020 Q1 March Q2 June Q3 September Q4 December Total revenue $ 88,489 $ 71,691 $ 74,329 $ 73,978 Gross profit 38,366 32,749 33,006 34,059 Income (loss) before provision (benefit) for income taxes (1,687 ) 3,525 (1,913 ) (5,205 ) Provision (benefit) for income taxes (98 ) 945 (214 ) (84 ) Net income (loss) (1,589 ) 2,580 (1,699 ) (5,121 ) Net income (loss) per share attributable to common stockholders: Basic $ (0.07 ) $ 0.12 $ (0.08 ) $ (0.23 ) Diluted (1) $ (0.07 ) $ 0.12 $ (0.08 ) $ (0.23 ) Weighted-average number of shares used in calculating net income (loss) per share attributable to common stockholders: Basic common shares 21,916,365 21,963,472 21,998,299 22,042,288 Diluted common shares 21,916,365 22,221,356 21,998,299 22,042,288 (1) Due to net loss for periods Q1 March, Q3 September, and Q4 December, diluted loss per share is the same as basic. (amounts in thousands, except share and per share amounts) Quarterly Results 2019 Q1 March Q2 June Q3 September Q4 December Total revenue $ 90,202 $ 101,063 $ 91,761 $ 78,917 Gross profit 44,409 50,215 43,315 33,922 Income (loss) before provision (benefit) for income taxes 6,072 13,684 8,753 (4,237 ) Provision (benefit) for income taxes 770 3,524 1,890 (2,862 ) Net income (loss) 5,302 10,160 6,863 (1,375 ) Net income (loss) per share attributable to common stockholders: Basic $ 0.24 $ 0.47 $ 0.31 $ (0.06 ) Diluted (2) $ 0.24 $ 0.45 $ 0.31 $ (0.06 ) Weighted-average number of shares used in calculating net income (loss) per share attributable to common stockholders: Basic common shares 21,750,305 21,815,634 21,840,473 21,878,004 Diluted common shares 22,534,885 22,359,679 22,191,688 21,878,004 (2) Due to net loss for period Q4 December, diluted loss per share is the same as basic. Comparison of years ended December 31, 2019 and 2018 A discussion of changes in our results of operations during the year ended December 31, 2019 compared to the year ended December 31, 2018 has been omitted from this Annual Report on Form 10-K but may be found in “Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations” in our Annual Report on Form 10-K for the year ended December 31, 2019, filed with the SEC on February 25, 2020, which discussion is incorporated herein by reference and which is available free of charge on the SECs website at www.sec.gov . 78 Liquidity and capital resources As of December 31, 2020, we had cash and cash equivalents of $212.0 million, which consisted of highly liquid investments with a maturity of three months or less. In addition, we held marketable securities of $19.3 million in available-for-sale corporate bonds, U.S. Treasury securities, and agency mortgage-backed securities, which had maturities greater than three months. For the years ended December 31, 2020, 2019 and 2018, we received $2.4 million, $5.9 million and $19.5 million, respectively, in proceeds related to stock option exercises and our employee stock purchase plan. Our principal uses of cash for liquidity and capital resources in the year ended December 31, 2020 consisted of capital expenditures of $17.6 million including additional rental equipment, other property, plant and equipment, and intangible assets. The COVID-19 pandemic and related PHE did not yet materially impact our liquidity position to date, and we believe our current cash and cash equivalents provide us with a certain degree of stability and liquidity during this time of uncertainty. We believe that our current cash, cash equivalents and the cash to be generated from expected product sales and rentals will be sufficient to meet our projected operating and investing requirements for at least the next twelve months. However, our liquidity assumptions may prove to be incorrect, and we could utilize our available financial resources sooner than we currently expect. Our future funding requirements will depend on many factors, including market acceptance of our products; the cost of our research and development activities; payments from customers; the cost, timing, and outcome of litigation or disputes involving intellectual property rights, our products, employee relations, cyber security incidents, or otherwise; the cost and timing of acquisitions; the cost and timing of regulatory clearances or approvals; the cost and timing of establishing additional sales, marketing, and distribution capabilities; and the effect of competing technological and market developments. In the future, we may acquire businesses or technologies from third parties, and we may decide to raise additional capital through debt or equity financing to the extent we believe this is necessary to successfully complete these acquisitions. Our future capital requirements will also depend on many additional factors, including those set forth in the section of this Annual Report on Form 10-K entitled “Risk Factors.” If we require additional funds in the future, we may not be able to obtain such funds on acceptable terms, or at all. In the future, we may also attempt to raise additional capital through the sale of equity securities or through equity-linked or debt financing arrangements. If we raise additional funds by issuing equity or equity-linked securities, the ownership of our existing stockholders will be diluted. If we raise additional financing by the incurrence of indebtedness, we will be subject to increased fixed payment obligations and could also be subject to restrictive covenants, such as limitations on our ability to incur additional debt, and other operating restrictions that could adversely impact our ability to conduct our business. Any future indebtedness we incur may result in terms that could be unfavorable to equity investors. There can be no assurances that we will be able to raise additional capital, which would adversely affect our ability to achieve our business objectives. In addition, if our operating performance during the next twelve months is below our expectations, our liquidity and ability to operate our business could be adversely affected. The following tables show a summary of our cash flows and working capital for the periods and as of the dates indicated: (amounts in thousands) Years ended December 31, Summary of consolidated cash flows 2020 2019 2018 Cash provided by operating activities $ 37,013 $ 40,593 $ 59,977 Cash used in investing activities (25,640 ) (44,057 ) (24,965 ) Cash provided by financing activities 2,066 4,929 18,296 Effect of exchange rates on cash 486 (62 ) 373 Net increase in cash and cash equivalents $ 13,925 $ 1,403 $ 53,681 79 (amounts in thousands) December 31, Working capital 2020 2019 Cash and cash equivalents $ 211,962 $ 198,037 Marketable securities 19,257 11,057 Accounts receivable, net 29,717 34,325 Inventories, net 24,815 35,664 Income tax receivable 2,048 2,976 Prepaid expenses and other current assets 17,898 10,160 Total current assets 305,697 292,219 Accounts payable and accrued expenses 33,712 30,730 Accrued payroll 7,091 6,215 Warranty reserve - current 5,740 4,923 Operating lease liability - current 1,931 2,014 Deferred revenue - current 6,994 5,478 Income tax payable 1,242 821 Total current liabilities 56,710 50,181 Net working capital $ 248,987 $ 242,038 Operating activities We derive operating cash flows from cash collected from the sales and rental of our products and services. These cash flows received are partially offset by our use of cash for operating expenses to support the growth of our business. Net cash provided by operating activities for the year ended December 31, 2020 consisted primarily of our non-cash expense items such as depreciation of equipment and leasehold improvements and amortization of our intangibles of $18.6 million, provision for sales returns and doubtful accounts of $10.5 million, stock-based compensation expense of $8.2 million, provision for rental revenue adjustments of $2.6 million, provision for inventory obsolescence and other inventory losses of $1.3 million, change in fair value of earnout liability of $1.1 million, net loss on disposal of rental equipment and other fixed assets of $0.9 million and our net loss of $5.8 million. The net changes in operating assets and liabilities resulted in no effect on cash flows from operating activities. Net cash provided by operating activities for the year ended December 31, 2019 consisted primarily of our net income of $21.0 million as well as non-cash expense items such as provision for sales returns and doubtful accounts of $17.2 million, depreciation of equipment and leasehold improvements and amortization of our intangibles of $13.8 million, stock-based compensation expense of $9.1 million, deferred tax assets of $2.9 million, provision for rental revenue adjustments of $2.2 million, provision for inventory obsolescence and other inventory losses of $1.0 million, change in fair value of earnout liability of $0.8 million and net loss on disposal of rental equipment and other fixed assets of $0.6 million. The net changes in operating assets and liabilities resulted in a net use of cash of $27.9 million. Net cash provided by operating activities for the year ended December 31, 2018 consisted primarily of our net income of $51.8 million and non-cash expense items such as provision for sales returns and doubtful accounts of $17.5 million, stock-based compensation expense of $12.8 million, depreciation of equipment and leasehold improvements and amortization of our intangibles of $11.3 million, provision for rental revenue adjustments of $2.7 million, and loss on disposal of rental equipment and other fixed assets of $1.2 million. These were partially offset by an increase in deferred tax assets of $11.6 million and gain on sale of former rental assets of $0.4 million. The net changes in operating assets and liabilities resulted in a net use of cash of $25.6 million. Investing activities Net cash used in investing activities for each of the periods presented included cash used for acquisitions and in the production and purchase of rental assets, manufacturing tooling, and computer equipment and software to support our expanding business as well as net (purchases) maturities of marketable securities. 80 For the year ended December 31, 20 20 , we invested $22.8 million in corporate bonds , U.S. Treasury securities and agency mortgage-backed securities with maturities greater than three months that were classified as marketable securities, partially offset by $14.5 million in maturities of available-for-sale investments . In addition, we invested $ 17.6 million in the production and purchase of rental assets and other property, equipment, and intangible assets. For the year ended December 31, 2019, we acquired New Aera for a net cash payment of $70.4 million and invested $58.7 million in corporate bonds and U.S. Treasury securities with maturities greater than three months that were classified as marketable securities, partially offset by $91.4 million in maturities of marketable securities. In addition, we invested $6.5 million in the production and purchase of rental assets and other property, equipment, leasehold improvements and intangible assets. For the year ended December 31, 2018, we invested $76.2 million in corporate bonds and U.S. Treasury securities with maturities greater than three months that were classified as marketable securities, partially offset by $63.5 million in maturities of available-for-sale investments. In addition, we invested $13.0 million in the production and purchase of rental assets, intangible assets and other property, equipment, and leasehold improvements, partially offset from gross proceeds received from the sale of former rental assets of $0.7 million. We expect to continue investing in property, equipment and leasehold improvements as we expand our operations. Our business is inherently capital intensive. For example, we expend significant manufacturing and production expense in connection with the development and production of our oxygen concentrator products and, in connection with our rental business, we incur expense in the deployment of rental equipment to our patients. Investments will continue to be required in order to grow our sales and rental revenue and continue to supply and replace rental equipment to our rental patients on service. Financing activities Historically, we have funded our operations through our sales and rental revenue, the issuance of preferred and common stock, and the incurrence of indebtedness. For the year ended December 31, 2020, net cash provided by financing activities consisted of $2.4 million from purchases under our employee stock purchase program and the proceeds received from stock options that were exercised, partially offset by the payment of employment taxes related to the vesting of restricted stock awards and restricted stock units of $0.4 million. For the year ended December 31, 2019, net cash provided by financing activities consisted of $5.9 million from the proceeds received from stock options that were exercised and purchases under our employee stock purchase program, partially offset by the payment of employment taxes related to the vesting of restricted stock awards and restricted stock units of $0.9 million. For the year ended December 31, 2018, net cash provided by financing activities consisted of $19.5 million from the proceeds received from stock options that were exercised and purchases under our employee stock purchase program, partially offset by the payment of employment taxes related to the vesting of restricted stock awards and restricted stock units of $1.2 million. Sources of funds Our cash provided by operating activities in the year ended December 31, 2020 was $37.0 million compared to $40.6 million in the year ended December 31, 2019. As of December 31, 2020, we had cash and cash equivalents of $212.0 million. Use of funds Our principal uses of cash are funding our new rental asset deployments and other capital purchases, operations, and other working capital requirements and, from time-to-time, the acquisition of businesses. Over the past several years, our revenue has increased from year-to-year and, as a result, our cash flows from customer collections have increased as have our profits. Our annual cash provided by operating activities has generally increased over time and has been a significant source of capital to the business, which we expect to continue in the future. We may need to raise additional funds to support our investing operations, and such funding may not be available to us on acceptable terms, or at all. If we are unable to raise additional funds when needed, our operations and ability to execute our business strategy could be adversely affected. We may seek to raise additional funds through equity, equity-linked or debt financings. If we raise additional funds through the incurrence of indebtedness, such indebtedness would have rights that are senior to holders of our equity securities and could contain covenants that restrict our operations. Any additional equity financing may be dilutive to our stockholders. 81 Non-GAAP financial measures EBITDA and Adjusted EBITDA are financial measures that are not calculated in accordance with U.S. GAAP. We define EBITDA as net income (loss) excluding interest income, interest expense, taxes and depreciation and amortization. Adjusted EBITDA also excludes stock-based compensation and change in fair value of earnout liability. Below, we have provided a reconciliation of EBITDA and Adjusted EBITDA to our net income (loss), the most directly comparable financial measure calculated and presented in accordance with U.S. GAAP. EBITDA and Adjusted EBITDA should not be considered alternatives to net income (loss) or any other measure of financial performance calculated and presented in accordance with U.S. GAAP. Our EBITDA and Adjusted EBITDA may not be comparable to similarly titled measures of other organizations because other organizations may not calculate EBITDA and Adjusted EBITDA in the same manner as we calculate these measures. We include EBITDA and Adjusted EBITDA in this Annual Report on Form 10-K because they are important measures upon which our management assesses our operating performance. We use EBITDA and Adjusted EBITDA as key performance measures because we believe they facilitate operating performance comparisons from period-to-period by excluding potential differences primarily caused by variations in capital structures, tax positions, the impact of depreciation and amortization expense on our fixed assets and intangible assets, the impact of stock-based compensation expense and the impact of the change in fair value of the earnout liability. Because EBITDA and Adjusted EBITDA facilitate internal comparisons of our historical operating performance on a more consistent basis, we also use EBITDA and Adjusted EBITDA for business planning purposes, to incentivize and compensate our management personnel, and in evaluating acquisition opportunities. In addition, we believe EBITDA and Adjusted EBITDA and similar measures are widely used by investors, securities analysts, ratings agencies, and other parties in evaluating companies in our industry as a measure of financial performance and debt-service capabilities. Our uses of EBITDA and Adjusted EBITDA have limitations as analytical tools and should not be considered in isolation or as a substitute for analysis of our results as reported under U.S. GAAP. Some of these limitations are: • EBITDA and Adjusted EBITDA do not reflect our cash expenditures for capital equipment or other contractual commitments; • although depreciation and amortization are non-cash charges, the assets being depreciated and amortized may have to be replaced in the future, and EBITDA and Adjusted EBITDA do not reflect capital expenditure requirements for such replacements; • EBITDA and Adjusted EBITDA do not reflect changes in, or cash requirements for, our working capital needs; • Adjusted EBITDA does not include changes in fair value of earnout liability related to our acquisitions; and • other companies, including companies in our industry, may calculate EBITDA and Adjusted EBITDA measures differently, which reduces their usefulness as a comparative measure. In evaluating EBITDA and Adjusted EBITDA, we anticipate that in the future we will incur expenses within these categories similar to this presentation. Our presentation of EBITDA and Adjusted EBITDA should not be construed as an inference that our future results will be unaffected by certain expenses. When evaluating our performance, EBITDA and Adjusted EBITDA should be considered alongside other financial performance measures, including U.S. GAAP results. The following tables present a reconciliation of EBITDA and Adjusted EBITDA to our net income (loss), the most comparable U.S. GAAP measure, for each of the periods indicated: (amounts in thousands) Years ended December 31, Non-GAAP EBITDA and Adjusted EBITDA 2020 2019 2018 Net income (loss) $ (5,829 ) $ 20,950 $ 51,845 Non-GAAP adjustments: Interest income (909 ) (4,712 ) (3,259 ) Provision (benefit) for income taxes 549 3,322 (11,390 ) Depreciation and amortization 18,581 13,834 11,295 EBITDA (non-GAAP) 12,392 33,394 48,491 Stock-based compensation 8,203 9,129 12,790 Change in fair value of earnout liability 1,053 810 — Adjusted EBITDA (non-GAAP) $ 21,648 $ 43,333 $ 61,281 82 Contractual obligations The following table reflects a summary of our contractual obligations as of December 31, 2020. Payments due by period (amounts in thousands) Less than 1-3 3-5 More than Contractual Obligations Total 1 year years years 5 years Operating leases - properties and other (1) $ 11,150 $ 2,224 $ 5,274 $ 576 $ 3,076 Non-cancelable contractual obligations (2) 457 457 — — — Purchase obligations (3) 60,200 60,200 — — — Total $ 71,807 $ 62,881 $ 5,274 $ 576 $ 3,076 (1) We lease manufacturing and office space in Richardson, TX, Plano, TX, Goleta, CA, Smyrna, TN, Huntsville, AL, Aurora, CO, Cleveland, OH and Breukelen, Netherlands with terms that expire between 2021 and 2031 and miscellaneous office and processing equipment in Texas, California and Ohio with terms expiring between 2021 and 2025. This table does not include lease payments for additional operating leases for our new corporate headquarters in California, industrial space in Texas, and office equipment in Ohio that have not yet commenced as of December 31, 2020, which have combined total minimum lease payments of $21.4 million. These operating leases will commence in 2021 with a lease term of 10-11 years for the facilities and 5 years for the office equipment. (2) These obligations are for software licenses and maintenance agreements. (3) We obtain individual components for our products from a wide variety of individual suppliers. Consistent with industry practice, we acquire components through a combination of purchase orders, supplier contracts, and open orders based on projected demand information. Where appropriate, the purchases are applied to inventory component prepayments that are outstanding with the respective supplier. As of December 31, 2020, we had noncurrent deferred tax liabilities of $14.4 million which were netted in noncurrent deferred tax assets on the balance sheet. Additionally, as of December 31, 2020, we had gross unrecognized tax benefits of $1.9 million. The table does not include any payments related to liabilities recorded for uncertain tax positions as we cannot make a reasonably reliable estimate as to the timing of any other payments. See Note 7 to our audited consolidated financial statements included elsewhere in this Annual Report on Form 10-K. Critical accounting policies and estimates Our discussion and analysis of our financial condition and results of operations are based upon our consolidated financial statements which have been prepared in accordance with generally accepted accounting principles in the United States of America, or U.S. GAAP. The preparation of these financial statements requires us to make estimates and judgments that affect the reported amounts of assets and liabilities and related disclosure of contingent assets and liabilities, revenue and expenses at the date of the financial statements. Generally, we base our estimates on historical experience and on various other assumptions in accordance with U.S. GAAP that we believe to be reasonable under the circumstances. Actual results may differ from these estimates and such differences could be material to the financial position and results of operations. Critical accounting policies and estimates are those that we consider the most important to the portrayal of our financial condition and results of operations because they require our most difficult, subjective or complex judgments, often as a result of the need to make estimates about the effect of matters that are inherently uncertain. Our critical accounting policies and estimates include those related to: ● revenue recognition; ● product warranty; and ● acquisitions and related acquired intangible assets and goodwill. Revenue recognition We generate revenue primarily from sales and rentals of our products. Our products consist of our proprietary line of oxygen concentrators and related accessories. Other revenue primarily comes from service contracts, replacement parts and freight revenue for product shipments. Revenue is recognized upon transfer of control of promised products or services to customers in an amount that reflects the consideration we expect to receive in exchange for those products or services. Revenue from product sales is generally recognized upon shipment of the product but is deferred for certain transactions when control has not yet transferred to the customer. 83 Our product is generally sold with a right of return and we may provide other incentives, which are accounted for as variable consideration when estimating the amount of revenue to recognize. Returns and incentives are estimated at the time sales revenue is recognized. The provisions for estimated returns are made based on known claims and estimates of additional returns based on historical data and future expectations. Sales revenue incentives within our contracts are estimated based on the most likely amounts expected on the related sales transaction and recorded as a reduction to revenue at the time of sale in accordance with the terms of the contract. Accordingly, revenue is recognized net of allowances for estimated returns and incentives. For a fixed price, we also offer a lifetime warranty for direct-to-consumer sales for our oxygen concentrators. The revenue is allocated to the distinct lifetime warranty performance obligation based on a relative stand-alone selling price (SSP) method. We have vendor-specific objective evidence of the selling price for our equipment. To determine the selling price of the lifetime warranty, we use the best estimate of the SSP for the distinct performance obligation as the lifetime warranty is neither separately priced nor is the selling price available through third-party evidence. To estimate the selling price associated with the lifetime warranties, management considers the profit margins of service revenue, the average estimated cost of lifetime warranties and the price of extended warranties. Revenue from the distinct lifetime warranty is deferred after the delivery of the equipment and recognized based on an estimated mortality rate over five years, which is the estimated performance period of the contract based on the average patient life expectancy. Revenue from the sale of our repair services is recognized when the performance obligations are satisfied, and collection of the receivables is probable. Other revenue from the sale of replacement parts is generally recognized when product is shipped to customers. Freight revenue consists of fees associated with the deployment of products internationally and domestically when expedited freight options are requested or when minimum order quantities are not met. Freight revenue is generally recognized upon shipment of the product but is deferred if control has not yet transferred to the customer. Shipping and handling costs for sold products and rental assets shipped to our customers are included on the consolidated statement of comprehensive income as part of cost of sales revenue and cost of rental revenue, respectively. The payment terms and conditions of customer contracts vary by customer type and the products and services offered. For certain products or services and customer types, we require payment before the products or services are delivered to the customer. The timing of sales revenue recognition, billing and cash collection results in billed accounts receivable and deferred revenue in the consolidated balance sheet. Contract liabilities primarily consist of deferred revenue related to lifetime warranties on direct-to-consumer sales revenue when cash payments are received in advance of services performed under the contract. The contract with the customer states the final terms of the sale, including the description, quantity, and price of each product or service purchase. We elected to apply the practical expedient in accordance with ASC 606 — Revenue Recognition and did not evaluate contracts of one year or less for the existence of a significant financing component . We do not expect any revenue to be recognized over a multi-year period with the exception of revenue related to lifetime warranties. We recognize equipment rental revenue over the non-cancelable lease term, which is one month, less estimated adjustments, per ASC 842— Leases . We have separate contracts with each patient that are not subject to a master lease agreement with any payor. We evaluate the individual lease contracts at lease inception and the start of each monthly renewal period to determine if there is reasonable assurance that the bargain renewal option associated with the potential capped free rental period would be exercised. Historically, the exercise of such bargain renewal option is not reasonably assured at lease inception and most subsequent monthly lease renewal periods. If we determine that the reasonable assurance threshold for an individual patient is met at lease inception or at a monthly lease renewal period, such determination would impact the bargain renewal period for an individual lease. We would first consider the lease classification (sales-type lease or operating lease) and then appropriately recognize or defer rental revenue over the lease term, which may include a portion of the capped rental period. To date, we have not deferred any amounts associated with the capped rental period. Amounts related to the capped rental period have not been material in the periods presented. The lease term begins on the date products are shipped to patients and are recorded at amounts estimated to be received under reimbursement arrangements with third-party payors, including Medicare, private payors, and Medicaid. Due to the nature of the industry and the reimbursement environment in which we operate, certain estimates are required to record net revenue and accounts receivable at their net realizable values. Inherent in these estimates is the risk that they will have to be revised or updated as additional information becomes available. Specifically, the complexity of many third-party billing arrangements and the uncertainty of reimbursement amounts for certain services from certain payors may result in adjustments to amounts originally recorded. Such adjustments are typically identified and recorded at the point of cash application, claim denial or account review. Accounts receivable are reduced by an allowance for doubtful accounts which provides for those accounts from which payment is not expected to be received, although product was delivered and revenue was earned. Upon determination that an account is uncollectable, it is written- 84 off and charged to the allowance. Amounts billed but not earned due to the timing of the billing cycle are deferred and recognized in revenue on a straight-line basis over the monthly billing period. For example, if the first day of the billing period does not fall on the first of the month, then a portion of the monthly billing period will fall in the subsequent month and the related revenue and cost would be deferred based on the service days in the following month. Rental revenue is recognized as earned, less estimated adjustments. Revenue not billed at the end of the period is reviewed for the likelihood of collections and accrued. The rental revenue stream is not guaranteed, and payment will cease if the patient no longer needs oxygen or returns the equipment. Revenue recognized is at full estimated allowable reimbursement rates. Rental revenue is earned for that month if the patient is on service on the first day of the 30-day period commencing on the recurring date of service for a particular claim regardless of whether there is a change in condition or death after that date. In the event that a third-party payor does not accept the claim for payment, the consumer is ultimately responsible for payment for the products and services. We have determined that the balances are collectable at the time of revenue recognition because the patient signs a notice of financial responsibility outlining their obligations. Included in rental revenue are unbilled amounts that were earned but not able to be billed for various reasons. The criteria for recognizing revenue had been met as of period-end, but there were specific reasons why we were unable to bill Medicare and private insurance for these amounts. As a result, we create an unbilled rental revenue accrual based on these earned revenues not billed based on a percentage of unbilled amounts and historical trends and estimates of future collectability. Product Warranty We generally provide a warranty against defects in material and workmanship. We provide a 3-year, 5-year or lifetime warranty on Inogen One systems sold and a 3-year and lifetime warranty on Inogen At Home systems sold. The TAV system has a 1-year and a 3-year warranty. We also offer a lifetime warranty for direct-to-consumer sales for our oxygen concentrators. For a fixed price, we agree to provide a fully functional oxygen concentrator for the remaining life of the patient. Lifetime warranties are only offered to patients upon the initial sale of oxygen concentrators directly from us and are non-transferable. Our products are subject to regulatory and quality standards. We establish an accrued liability for the estimated warranty costs at the time of revenue recognition, with a corresponding provision to cost of goods sold. We evaluate the liability quarterly. Warranty costs are primarily estimated based on product return rates, historical warranty repair costs incurred and historical failure rates. We may make further adjustments to the warranty reserve when deemed appropriate, giving additional consideration to length of time the product version has been sold and future expectations of performance based on new features and capabilities. Actual warranty costs could differ materially from the estimated amounts. Acquisitions and related acquired intangible assets and goodwill The purchase price of an acquisition is allocated to the underlying assets acquired and liabilities assumed based upon their estimated fair values at the date of acquisition. To the extent the purchase price exceeds the fair value of the net identifiable tangible and intangible assets acquired and liabilities assumed, such excess is allocated to goodwill. We may adjust the preliminary purchase price allocation, as necessary, for up to one year after the acquisition closing date if we obtain more information regarding asset valuations and liabilities assumed. We acquired New Aera on August 9, 2019 for $101.9 million. The excess purchase price over the fair value of net tangible assets and identifiable intangible assets acquired has been allocated to goodwill. Goodwill represents the expected synergies with the existing business, the acquired assembled workforce, and future cash flows after the acquisition. The fair value assigned to the identifiable intangible asset was determined primarily by using the excess earnings method. The key assumptions included in the excess earnings method included revenue recognized, cost of revenue and the discount rate. Goodwill is tested for impairment on an annual basis as of October 1. Interim testing of goodwill for impairment is also required whenever an event occurs or circumstances change that would more likely than not reduce the fair value of a reporting unit or asset below its carrying amount. No impairments were recorded as of December 31, 2020 and December 31, 2019. Finite-lived intangible assets are amortized over their useful lives and are tested for recoverability whenever events or changes in circumstances indicate that the carrying amount may not be recoverable. Technology and customer relationship intangibles are amortized using the straight-line method. 85 Recent accounting pronouncements Refer to Note 1 – Summary of significant accounting policies of the audited consolidated notes included in Part II, Item 8, "Financial Statements and Supplementary Data" in this Annual Report on Form 10-K for further discussion. Off-balance sheet arrangements We do not have any relationships with unconsolidated entities or financial partnerships, such as entities often referred to as structured finance or special purpose entities, which would have been established for the purpose of facilitating off-balance sheet arrangements or for any other contractually narrow or limited purpose. However, from time-to-time, we enter into certain types of contracts that contingently require us to indemnify parties against third-party claims including certain real estate leases, supply purchase agreements, and directors and officers. The terms of such obligations vary by contract and in most instances a maximum dollar amount is not explicitly stated therein. Generally, amounts under these contracts cannot be reasonably estimated until a specific claim is asserted thus no liabilities have been recorded for these obligations on our balance sheets for any of the periods presented. Inflation We do not believe that inflation has had a material effect on our business, financial condition or results of operations. If our costs were to become subject to significant inflationary pressures, we might not be able to fully offset such higher costs through price increases. Our inability or failure to do so could harm our business, financial condition and results of operations.