BARRETT BUSINESS SERVICES INC 10-Q

Item 5. Other Information Trading Plans During the quarter ended June 30, 2026 , none of our directors or executive officers adopted or terminated a “Rule 10b5-1 trading arrangement” or a “non-Rule 10b5-1 trading arrangement” (as each term is defined in Item 408 of Regulation S-K). 30 Item 6. Exhibits 31.1 Certification of Chief Executive Officer pursuant to Rule 13a-14(a). 31.2 Certification of Chief Financial Officer pursuant to Rule 13a-14(a). 32* Certification pursuant to 18 U.S.C. Section 1350. 101.INS Inline XBRL Instance Document- the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document. 101.SCH Inline XBRL Taxonomy Extension Schema Document 101.CAL Inline XBRL Taxonomy Extension Calculation Linkbase Document 101.DEF Inline XBRL Taxonomy Extension Definition Linkbase Document 101.LAB Inline XBRL Taxonomy Extension Label Linkbase Document 101.PRE Inline XBRL Taxonomy Extension Presentation Linkbase Document 104 The cover page from the Company’s Quarterly Report on Form 10-Q for the quarter ended June 30, 2026, has been formatted in Inline XBRL. * Furnished, not filed. SIGNAT URES Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized. BARRETT BUSINESS SERVICES, INC. Registrant Date: August 5, 2026 By: /s/ Anthony J. Harris Anthony J. Harris Executive Vice President and Chief Financial Officer and Treasurer 31