Executive Change · Reg FD Disclosure

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): August 20, 2025 DELUXE CORPORATION (Exact name of registrant as specified in its charter) MN 1-7945 41-0216800 (State or other jurisdiction (Commission (I.R.S. Employer of incorporation) File Number) Identification No.) 801 S. Marquette Ave. , Minneapolis , MN 55402-2807 (Address of principal executive offices) (Zip Code) ( 651 ) 483-7111 Registrant's telephone number, including area code Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions: ☐ Written communication pursuant to Rule 425 under the Securities Act (17 CFR 230.425) ☐ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) ☐ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) ☐ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)) Securities registered pursuant to Section 12(b) of the Act: Title of each class Trading symbol(s) Name of each exchange on which registered Common stock, par value $1.00 per share DLX NYSE Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter). ☐ Emerging growth company If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐ Section 5 - Corporate Governance and Management Item 5.02 Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers. On August 20, 2025, the Board of Directors (the “Board”) of Deluxe Corporation (the “Company”) unanimously elected Michelle T. Collins to the Board, effective August 20, 2025. Ms. Collins will stand for re-election at the Company’s 2026 Annual Meeting of the Shareholders. The Board has determined that Ms. Collins qualifies as an independent director under the listing standards of the New York Stock Exchange and the Company’s director independence standards, as adopted by the Board. The Board has also determined that Ms. Collins has sufficient accounting or related financial management expertise to serve as an “audit committee financial expert” as defined by the SEC in Item 407(d)(5)(ii) of Regulation S-K. As such, Ms. Collins also qualifies as a financial expert pursuant to 303A.07 of the NYSE Listed Company Manual. Ms. Collins will serve on the Company’s Audit and Finance Committee and a second committee to be determined at a later date. Ms. Collins recently served as Vice Chair and a member of Deloitte’s U.S. Board of Directors. During her six-year tenure on the Board, she served as the Chair of the Governance Committee and Chair of the Finance and Audit Committee. During her career with Deloitte, Ms. Collins advised across a broad spectrum of issues, including business transformations, mergers and acquisitions, enterprise risk management, financial accounting and reporting, and SEC compliance. Ms. Collins also serves as a member of the board of directors of Owens Corning. Ms. Collins earned a bachelor’s degree in accounting from Western Michigan University and is a Certified Public Accountant. Section 7 - Regulation FD Item 7.01 Regulation FD Disclosure. A copy of the Company’s press release announcing the election of Ms. Collins to the Board is furnished herewith as Exhibit 99.1. 2 Section 9 - Financial Statements and Exhibits Item 9.01 Financial Statements and Exhibits. (d) Exhibits. Exhibit Number Description 99.1 Press Release, dated August 20, 2025, of Deluxe Corporation 101.INS 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 XBRL Taxonomy Extension Schema Document 101.LAB XBRL Taxonomy Extension Label Linkbase Document 101.PRE XBRL Taxonomy Extension Presentation Linkbase Document 104 Cover page interactive data file (formatted as Inline XBRL and contained in Exhibit 101) 3 SIGNATURES Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized. Date: August 21, 2025 DELUXE CORPORATION /s/ Jeffrey L. Cotter Jeffrey L. Cotter Senior Vice President, Chief Administrative Officer and General Counsel 4