X0202 SCHEDULE 13D/A 0001594487 XXXXXXXX LIVE 21 Common Stock 09/01/2026 false 0001590955 70432V102 PAYCOM SOFTWARE, INC.

7501 W. Memorial Road Oklahoma City OK 73142

Greg R. Samuel, Esq. (214) 651-5000 Haynes and Boone, LLP 2801 N Harwood St, Suite 2300 Dallas TX 75201 Rosebud Nau, Esq. (214) 651-5000 Haynes and Boone, LLP 2801 N Harwood St, Suite 2300 Dallas TX 75201 0001607049 N Ernest Group, Inc. a OO N OK 0 3217249 0 3217249 3217249 N 7.1 CO 0001594487 N Chad Richison a OO N X1 2674328 3225379 2674328 3225379 5899707 N 13.1 IN (1) The figure reported in Items 8 and 10 on this cover page consists of (a) 3,217,249 shares of Common Stock owned by Ernest Group, (b) 56 shares of Common Stock owned by the ARR Trust, (c) 440 shares of Common Stock owned by the ALR Trust, (d) 440 shares of Common Stock owned by the IDR Trust, (e) 1,199 shares of Common Stock owned by the RWP Trust, (f) 1,199 shares of Common Stock owned by the LWR Trust, (g) 1,199 shares of Common Stock owned by the KGR Trust, (h) 1,199 shares of Common Stock owned by the SER Trust, (i) 1,199 shares of Common Stock owned by the CBP Trust, and (j) 1,199 shares of Common Stock owned by the FPR Trust. (2) The figure reported in Item 11 on this cover page consists of (a) 2,674,328 shares of Common Stock owned by Mr. Richison, (b) 3,217,249 shares of Common Stock owned by Ernest Group, (c) 56 shares of Common Stock owned by the ARR Trust, (d) 440 shares of Common Stock owned by the ALR Trust, (e) 440 shares of Common Stock owned by the IDR Trust, (f) 1,199 shares of Common Stock owned by the RWP Trust, (g) 1,199 shares of Common Stock owned by the LWR Trust, (h) 1,199 shares of Common Stock owned by the KGR Trust, (i) 1,199 shares of Common Stock owned by the SER Trust, (j) 1,199 shares of Common Stock owned by the CBP Trust, and (k) 1,199 shares of Common Stock owned by the FPR Trust. Common Stock PAYCOM SOFTWARE, INC. 7501 W. Memorial Road Oklahoma City OK 73142 This Amendment No. 21 to Schedule 13D (this "Amendment") relates to shares of common stock, par value $0.01 per share ("Common Stock"), of Paycom Software, Inc., a Delaware corporation (the "Issuer"). This Amendment amends the Schedule 13D (as previously amended or amended and restated and as amended and/or restated hereby, the "Schedule 13D") filed with the Securities and Exchange Commission (the "SEC") by the Reporting Persons. Capitalized terms used but not defined herein shall have the meanings ascribed to them in the Schedule 13D. Item 4 is hereby amended and supplemented as follows: "On September 1, 2026, Ernest Group entered into a Sales Plan (the "September 2026 10b5-1 Plan") with JPMS, pursuant to which JPMS is authorized to sell up to 1,090,000 shares of Common Stock on behalf of Ernest Group during the period beginning on the later of (i) December 1, 2026 and (ii) the third trading day following disclosure of the Issuer's financial results on Form 10-Q for the quarter ended September 30, 2026, and ending June 1, 2027, subject to earlier termination in accordance with the terms of the September 2026 10b5-1 Plan and applicable laws, rules and regulations. Transactions under the September 2026 10b5-1 Plan will be subject to certain price restrictions and other restrictions under the terms of the September 2026 10b5-1 Plan. The September 2026 10b5-1 Plan is intended to comply with the requirements of Rule 10b5-1(c) promulgated under the Act. The foregoing description of the September 2026 10b5-1 Plan is qualified in its entirety by reference to the full text of the September 2026 10b5-1 Plan, a form of which is attached hereto as Exhibit 99.6 and incorporated herein by reference." Item 5(a) is hereby amended and restated in its entirety as follows: "The aggregate number and percentage of the class of securities identified pursuant to Item 1 beneficially owned by each Reporting Person is stated in Items 11 and 13 on the cover pages hereto. The percentage reported in Item 13 on the cover pages hereto is based on 45,071,619 shares of Common Stock outstanding, including 786,338 shares of restricted stock, as of July 28, 2026, as disclosed in the Quarterly Report on Form 10-Q for the quarter ended June 30, 2026, filed by the Issuer with the SEC on August 6, 2026. Each Reporting Person declares that neither the filing of this Schedule 13D nor anything herein shall be construed as an admission that such person is, for the purposes of Section 13(d) or 13(g) of the Act or any other purpose, the beneficial owner of any securities covered by this Schedule 13D. Each Reporting Person may be deemed to be a member of a group with respect to the Issuer or securities of the Issuer for the purposes of Section 13(d) or 13(g) of the Act. Each Reporting Person declares that neither the filing of this Schedule 13D nor anything herein shall be construed as an admission that such person is, for the purposes of Section 13(d) or 13(g) of the Act or any other purpose, (i) acting (or has agreed or is agreeing to act) with any other person as a partnership, limited partnership, syndicate or other group for the purpose of acquiring, holding or disposing of securities of the Issuer or otherwise with respect to the Issuer or any securities of the Issuer; or (ii) a member of any syndicate or group with respect to the Issuer or any securities of the Issuer." Item 5(b) is hereby amended and restated in its entirety as follows: "Number of shares as to which each Reporting Person has: (i) sole power to vote or to direct the vote: See Item 7 on the cover pages hereto. (ii) shared power to vote or to direct the vote: See Item 8 on the cover pages hereto. (iii) sole power to dispose or to direct the disposition of: See Item 9 on the cover pages hereto. (iv) shared power to dispose or to direct the disposition of: See Item 10 on the cover pages hereto." Item 5(c) is hereby amended and restated in its entirety as follows: "There were no transactions in the shares of Common Stock that were effected during the past sixty days by the Reporting Persons or since the most recent Schedule 13D filing, whichever is less." Item 6 is hereby amended and supplemented as follows: "The information set forth in Item 4 of this Amendment is incorporated by reference into this Item 6." Item 7 is hereby amended and restated in its entirety as follows: "The following exhibits are filed as exhibits hereto: 99.1 Joint Filing Agreement, dated August 10, 2023, by and between Chad Richison and Ernest Group, Inc. (incorporated by reference to Exhibit 99.1 to the Schedule 13D filed by the Reporting Persons with the SEC on August 11, 2023). 99.2 Form of Sales Plan, dated December 15, 2025, by and between Ernest Group, Inc. and J.P. Morgan Securities LLC (incorporated by reference to Exhibit 99.4 to the Schedule 13D filed by the Reporting Persons with the SEC on December 17, 2025). 99.3 Paycom Software, Inc. 2023 Long-Term Incentive Plan (incorporated by reference to Exhibit 99.1 to the Issuer's Registration Statement on Form S-8 dated May 1, 2023, filed by the Issuer with the SEC on May 1, 2023). 99.4 Form of Restricted Stock Unit Award Agreement - Time-Based Vesting (Executive) under the Paycom Software, Inc. 2023 Long Term Incentive Plan (incorporated by reference to Exhibit 10.3.2 to the Issuer's Annual Report on Form 10-K for the year ended December 31, 2025, filed by the Issuer with the SEC on February 19, 2026). 99.5 Form of Restricted Stock Unit Award Agreement - Performance-Based Vesting under the Paycom Software, Inc. 2023 Long-Term Incentive Plan (incorporated by reference to Exhibit 10.3.4 to the Issuer's Annual Report on Form 10-K for the year ended December 31, 2025, filed by the Issuer with the SEC on February 19, 2026). 99.6* Form of Sales Plan, dated September 1, 2026, by and between Ernest Group, Inc. and J.P. Morgan Securities LLC." * Filed herewith Ernest Group, Inc. /s/ Chad Richison 09/03/2026 Chad Richison /s/ Chad Richison 09/03/2026