EXHIBIT 23 Consent of Independent Registered Public Accounting Firm
We consent to the incorporation by reference in the Registration Statement (Form S-8 No. 333-84055)
pertaining to the Paychex, Inc. 401(k) Incentive Retirement Plan of our report dated June 27, 2011,
with respect to the financial statements and schedule of Paychex, Inc. 401(k) Incentive Retirement
Plan included in this Annual Report (Form 11-K) for the year ended December 31, 2010.
June 27, 2011
Chicago, Illinois
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