DEFA14A

SCHEDULE 14A(Rule 14a-101)INFORMATION REQUIRED IN PROXY STATEMENTProxy Statement Pursuant to Section 14(a) ofthe Securities Exchange Act of 1934(Amendment No.  )

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☐ Preliminary Proxy Statement

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☐ Definitive Proxy Statement

☒ Definitive Additional Materials

☐ Soliciting material Pursuant to Rule 14a-12

AUTOMATIC DATA PROCESSING, INC.

(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

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On September 22, 2017, Automatic Data Processing, Inc. (“ADP” or the “Company”) sent the letter attached as Exhibit 1 hereto to William A. Ackman at Pershing Square Capital Management, L.P.

Additional Information

ADP, its directors and certain of its executive officers may be deemed to be participants in the solicitation of proxies from Company shareholders in connection with the matters to be considered at the Company’s 2017 Annual Meeting. The Company has filed a definitive proxy statement and WHITE proxy card with the U.S. Securities and Exchange Commission (the “SEC”) in connection with any such solicitation of proxies from Company shareholders. COMPANY SHAREHOLDERS ARE STRONGLY ENCOURAGED TO READ THE DEFINITIVE PROXY STATEMENT AND ACCOMPANYING WHITE PROXY CARD AS THEY CONTAIN IMPORTANT INFORMATION. Information regarding the identity of potential participants, and their direct or indirect interests, by security holdings or otherwise, is set forth in the proxy statement and other materials to be filed with the SEC. Shareholders will be able to obtain any proxy statement, any amendments or supplements to the proxy statement and other documents filed by the Company with the SEC for no charge at the SEC’s website at www.sec.gov. The proxy statement and other relevant documents filed by ADP with the SEC are also available, without charge, by directing a request to ADP’s proxy solicitor, Innisfree M&A Incorporated, 501 Madison Avenue, 20th Floor, New York, New York 10022; call toll-free:(877) 750-0510 or call collect: (212) 750-5833.Copies will also be available at no charge at the Company’s website at www.adp.com.

EX-99.1

EXHIBIT 1

Automatic Data Processing, Inc. One ADP Boulevard Roseland, New Jersey  07068-1728 (973) 974-5000

September 22, 2017

William A. Ackman

Pershing Square Capital Management, L.P.

888 Seventh Avenue, 42^nd Floor

New York, New York 10019

Dear Bill:

I am writing in response to your letter to the Board of Directors of Automatic Data Processing Inc. of September 15, 2017, requesting that the ADP Board allow the use of a “universal proxy card” process in connection with the 2017 Annual Meeting of Stockholders. 

The Board has carefully considered your request and has concluded that switching from the customary voting procedures that have been used in virtually every contested election to a new and untested universal voting card process would result in significant risks of confusion and disenfranchisement for our stockholders.  We therefore reject your request.  Our decision was based on the following concerns:

— Universal proxy card processes are not widely used by U.S. public companies and we are not aware of a single instance in which such a process has ever been employed by a large-cap, broadly held U.S. public company such as ADP.  The Securities and Exchange Commission has considered adopting the use of a universal proxy card process but has not done so, and therefore there are no rules or procedures that have been enacted to govern such a process. On the other hand, the customary voting card process is the subject of time-tested SEC rules and regulations, is extremely well understood by all categories of stockholders and has consistently resulted in fully informed stockholders and fair, accurate director elections.  In light of the great importance to stockholders of the outcome of this year’s election, the Board does not support experimenting with a new and untested voting process.

— The universal proxy card process is particularly problematic for a company with a retail stockholder base as large as that of ADP.  ADP has approximately 310,000 individual stockholders.  The process you propose would not allow stockholders to do what they have done in virtually every contested election to date--voting by simply executing and returning the proxy card.  Furthermore, we believe that existing “street name” voting infrastructure does not fully support universal proxy card voting, creating significant risk of confusion and delay that could result in disenfranchisement of retail holders.  The Board cannot condone a process that may deny stockholders the full and fair exercise of their voting rights.

— Switching to a universal proxy card process at this stage, after both ADP and Pershing Square have distributed proxy materials, would require each side to produce and distribute replacement proxy materials, implement new proxy collection mechanics and attempt to educate stockholders on new and novel voting procedures.  The Board believes that such a disruptive action taken after proxy solicitation has already begun will inevitably result in confusion among stockholders and interfere with the conduct of a fair and accurate election.

The outcome of this director election is of great importance to the future of ADP and its stockholders.  Changing the voting procedures after the stockholder solicitation has commenced to a new and untested process that could result in the disenfranchisement of a significant portion of ADP stockholders is not a decision the Board can support.  The existing voting procedures are governed by SEC rules and regulations, allow a clear choice to stockholders and will result in a fair, accurate and reliable election.

Sincerely,

John Jones

Chairman, ADP