Company: ADP
Filing Date: 2025-05-07
Form Type: 424B2
Source: 0001193125-25-114878
Chunk: 8

Company: AUTOMATIC DATA PROCESSING INC
Filing Date: 2025-05-07
Form: 424B2
Chunk 8
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urchase the Notes upon a Change of Control Triggering Event, however, because we may not have sufficient funds to do so. In addition, agreements governing indebtedness we may incur in the future may restrict us from purchasing the Notes in the
event of a Change of Control Triggering Event. Our failure to repurchase properly tendered Notes would constitute an event of default under the indenture governing the Notes. See “Description of Notes—Change of Control Offer.”

S-7

USE OF PROCEEDS

We will receive net proceeds from the offering of the Notes of approximately $988.3 million after deducting underwriting discounts,
commissions, costs related to interest rate hedges and estimated offering expenses. We intend to use the net proceeds of this offering to refinance existing debt, and any remainder for general corporate purposes.

S-8

CAPITALIZATION The following table sets forth a summary of our capitalization on a consolidated basis as of March 31, 2025. We have presented our capitalization on both an actual and an as adjusted basis to reflect the issuance and sale of the Notes offered hereby, but not the application of the net proceeds from the issuance and sale of the Notes. See “Use of Proceeds.” This table should be read in conjunction with our consolidated financial statements and the related notes incorporated by reference in this prospectus supplement and the accompanying prospectus.

|                                                                                              |     | As of March 31, 2025           |           |   |     |                     |           |   |
|:---------------------------------------------------------------------------------------------|:----|:-------------------------------|----------:|:--|:----|:--------------------|----------:|:--|
|                                                                                              |     | Actual                         |           |   |     | As Adjusted for the 
 Offering            |           |   |
|                                                                                              |     | -in millions, except per share 
 amounts                        |           |   |     |                     |           |   |
| Cash and Cash Equivalents                                                                    |     | $                              |   2,680.6 |   |     | $                   |   3,668.9 |   |
| Debt of subsidiaries:                                                                        |     |                                |           |   |     |                     |           |   |
| Obligations under reverse repurchase agreements                                              |     |                                |         — |   |     |                     |         — |   |
| Other short-term debt                                                                        |     |                                |       1.1 |   |     |                     |       1