Company: PAYX
Filing Date: 2025-04-08
Form Type: 424B2
Source: 0001193125-25-075170
Chunk: 60

Company: PAYCHEX INC
Filing Date: 2025-04-08
Form: 424B2
Chunk 60
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 prospectus and any risk factors described in any applicable prospectus supplement, as well as those risk factors in “Part I – Item 1A. Risk Factors” of our Annual Report on Form 10-Kfor the year ended May 31, 2024, as filed with the Securities and Exchange Commission, which is incorporated by reference herein, as well as in any other recently filed quarterly or current reports.

Neither the
Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or passed upon the adequacy or accuracy of this prospectus or any applicable prospectus supplement. Any representation to the
contrary is a criminal offense.

The date of this prospectus is March 31, 2025.

TABLE OF CONTENTS

|                                                      |     | Page |    |
| About this Prospectus                                |     |      |  1 |
| Cautionary Note Regarding Forward-Looking Statements |     |      |  2 |
| About the Company                                    |     |      |  4 |
| Risk Factors                                         |     |      |  5 |
| Use of Proceeds                                      |     |      |  6 |
| Description of Debt Securities                       |     |      |  7 |
| Plan of Distribution                                 |     |      | 16 |
| Legal Matters                                        |     |      | 18 |
| Experts                                              |     |      | 18 |
| Where You Can Find More Information                  |     |      | 19 |
| Incorporation of Certain Documents by Reference      |     |      | 19 |

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ABOUT THIS PROSPECTUS

This prospectus is part of a registration statement on Form S-3 that we filed with the Securities and
Exchange Commission, or SEC, using the “shelf” registration process. Under this shelf registration process, we may sell any combination of the securities described in this prospectus in one or more offerings. This prospectus provides you
with a general description of the securities we may offer. Each time we sell securities, we will provide a prospectus supplement that will contain specific information about the terms of that offering. The prospectus supplement may also add, update
or change information contained in this prospectus. Any statement that we make in this prospectus will be modified or superseded by any inconsistent statement made by us in a prospectus supplement.

You should read both this prospectus and any applicable prospectus supplement together with the additional information about our company to
which we refer you in