Company: NSP
Filing Date: 2025-04-15
Form Type: DEF 14A
Source: 0001000753-25-000013
Chunk: 1

Company: INSPERITY, INC.
Filing Date: 2025-04-15
Form: DEF 14A
Chunk 1
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 by completing and returning the enclosed proxy card or voting instruction card in the envelope provided. You may also attend and vote at the meeting by following the procedures that we have described in the proxy statement.

Thank you for your continued support and investment in our business. We look forward to seeing you at the meeting.

Sincerely,

Paul J. Sarvadi

Chairman of the Board and Chief Executive Officer

<div align='center'>NOTICE OF ANNUAL MEETING OF STOCKHOLDERS OF INSPERITY, INC.</div>

#### Date:

#### May 20, 2025

#### Time:

#### 1:30 p.m. Houston, Texas time
Place: The Auditorium in Centre I of our corporate headquarters

19001 Crescent Springs Drive, Kingwood, Texas 77339

At the meeting, stockholders will consider and act upon the following matters:

1. To elect the four nominees named in the proxy statement to the Board of Directors;

2. To cast an advisory vote to approve executive compensation (“say-on-pay” vote);

3. To approve the First Amendment to the Insperity, Inc. Incentive Plan; and

4. To ratify the appointment of Ernst & Young LLP as our independent registered public accounting firm for the year ending December 31, 2025.

Important Notice Regarding the Availability of Proxy Materials: A full set of all proxy materials for the Annual Meeting of Stockholders to be held on May 20, 2025 is enclosed with this notice. Additionally, the Company’s proxy statement, most recent annual report on Form 10-K, and other proxy materials are available at https://ir.insperity.com/investor-relations/annual-meetings.

Only stockholders of record at the close of business on April 4, 2025 are entitled to notice of, and to vote at, the meeting.

| It is important that your shares be represented at the Annual Meeting of Stockholders regardless of whether you plan to attend. Therefore, please submit your proxy via the Internet or telephone or by completing and returning the enclosed proxy card or voting instruction card. |

By Order of the Board of Directors

Christian P. Callens

Senior Vice President of Legal, General Counsel and Secretary

April 14, 2025

Kingwood, Texas

### TABLE OF CONTENTS
| Solicitation                                                                                |     |  1 |
| Questions and Answers About Voting and the Annual Meeting                                   |     |  1 |
| Security Ownership                                                                          |