Item (10) Associates/Acting In Concert continued:

If you checked the box in item #10 on the reverse side of this form, list below all other orders submitted by you or your associates (as defined below) or by persons acting in concert with you (also defined below).

Associate - The term “associate” of a particular person means:

(1) a corporation or organization, other than PCSB Financial Corporation or PCSB Bank, of which a person is a senior officer or partner or is, directly or indirectly, the beneficial owner of 10% or more of any class of equity securities of such corporation or organization;

(2) a trust or other estate in which a person has a substantial beneficial interest or as to which a person serves as a trustee or a fiduciary; and

(3) any person who is related by blood or marriage to such person and who lives in the same home as such person or who is a trustee, director or officer of PCSB Bank, PCSB Financial Corporation or any of their parents or subsidiaries.

Acting in concert – The term “acting in concert” means:

(1) knowing participation in a joint activity or interdependent conscious parallel action towards a common goal whether or not pursuant to an express agreement or understanding; or

(2) a combination or pooling of voting or other interests in the securities of an issuer for a common purpose pursuant to any contract, understanding, relationship, agreement or other arrangement, whether written or otherwise.

In general, a person who acts in concert with another party will also be deemed to be acting in concert with any person who is also acting in concert with that other party.

We may presume that certain persons are acting in concert based upon various facts, among other things, joint account relationships, common address on our records, and the fact that such persons may have filed joint Schedules 13D or 13G with the Securities and Exchange Commission with respect to other companies.

CERTIFICATION FORM

I ACKNOWLEDGE THAT THIS SECURITY IS NOT A DEPOSIT OR SAVINGS ACCOUNT AND IS NOT FEDERALLY INSURED OR GUARANTEED BY THE FEDERAL DEPOSIT INSURANCE CORPORATION, AND IS NOT INSURED OR GUARANTEED BY PCSB FINANCIAL CORPORATION, PCSB BANK, THE FEDERAL GOVERNMENT OR BY ANY GOVERNMENT AGENCY. THE ENTIRE AMOUNT OF AN INVESTOR’S PRINCIPAL IS SUBJECT TO LOSS.

I further certify that, before purchasing the common stock of PCSB Financial Corporation (the “Company”), I received a prospectus of the Company dated _____, 2017 relating to such offer of common stock. The prospectus that I received contains disclosure concerning the nature of the common stock being offered by the Company and describes in the “Risk Factors” section the risks involved in the investment in this common stock, including but not limited to the following:

Risks Related to Our Business

[insert final text]

Risks Related to the Offering

(By Signing the Front of this Form the Investor is Not Waiving Any Rights Under the Federal Securities Laws,

Including the Securities Act of 1933 and the Securities Exchange Act of 1934)

Individual

Include the first name, middle initial and last name of the stockholder. Avoid the use of two initials. Please omit words that do not affect ownership rights, such as “Mrs.”, “Mr.”, “Dr.”, “special account”, “single person”, etc.

Joint Tenants

Joint tenants with right of survivorship may be specified to identify two or more owners. When stock is held by joint tenants with right of survivorship, ownership is intended to pass automatically to the surviving joint tenant(s) upon the death of any joint tenant. All parties must agree to the transfer or sale of shares held by joint tenants.

Tenants in Common

Tenants in common may also be specified to identify two or more owners. When stock is held by tenants in common, upon the death of one co-tenant, ownership of the stock will be held by the surviving co-tenant(s) and by the heirs of the deceased co-tenant. All parties must agree to the transfer or sale of shares held by tenants in common.

Uniform Transfers to Minors Act (“UTMA”)

Stock may be held in the name of a custodian for a minor under the Uniform Transfers to Minors Act of each state. There may be only one custodian and one minor designated on a stock certificate. The standard abbreviation for Custodian is “CUST”, while the Uniform Transfers to Minors Act is “UTMA”. Standard U.S. Postal Service state abbreviations should be used to describe the appropriate state. For example, stock held by John Doe as custodian for Susan Doe under the NY Uniform Transfers to Minors Act will be abbreviated John Doe, CUST Susan Doe UTMA NY (use minor’s social security number).

Fiduciaries

Information provided with respect to stock to be held in a fiduciary capacity must contain the following:

•    The name(s) of the fiduciary. If an individual, list the first name, middle initial and last name. If a corporation, list the full corporate title (name). If an individual and a corporation, list the corporation’s title before the individual.

•    The fiduciary capacity, such as administrator, executor, personal representative, conservator, trustee, committee, etc.

•    A description of the document governing the fiduciary relationship, such as a trust agreement or court order. Documentation establishing a fiduciary relationship may be required to register your stock in a fiduciary capacity.

•    The date of the document governing the relationship, except that the date of a trust created by a will need not be included in the description.

•    The name of the maker, donor or testator and the name of the beneficiary.

An example of fiduciary ownership of stock in the case of a trust is: John Doe, Trustee Under Agreement Dated 10-1-93 for Susan Doe.

Items 1 and 2 - Number of Shares and Total Payment Due

Fill in the number of shares that you wish to purchase and the total payment due. The amount due is determined by multiplying the number of shares by the subscription price of $10.00 per share. The minimum purchase is 25 shares ($250) of common stock. As more fully described in the plan of conversion outlined in the prospectus, the maximum allowable purchase by a person, entity or group of people through a single account is 20,000 shares ($200,000) of common stock. No person, together with associates and persons acting in concert with such person, may purchase in the aggregate more than 30,000 shares ($300,000) of common stock.

Item 3 - Employee/Officer/Trustee/Director Information

Check this box to indicate whether you are an employee, officer, trustee or director of PCSB Bank or PCSB Financial Corporation, or a depositor of such person’s immediate family living in the same household.

Item 4 - Payment by Check

If you pay for your stock by check, bank draft or money order, indicate the total amount in this box. Payment for shares may be made by check, bank draft or money order payable to PCSB Financial Corporation Your funds will earn interest at 0.10% until the stock offering is completed or terminated.

Item 5 - Payment by Withdrawal

If you pay for your stock by a withdrawal from a deposit account at PCSB Bank, indicate the account number(s) and the amount of your withdrawal authorization for each account. The total amount withdrawn should equal the amount of your stock purchase. There will be no penalty assessed for early withdrawals from certificate of deposit accounts used for stock purchases. This form of payment may not be used if your account is an Individual Retirement Account.

Item 6 – Purchaser Information

Subscription Offering

a. Check this box if you had a deposit account(s) at PCSB Bank totaling $100.00 or more on September 30, 2015 (“Eligible Account Holder”).

b. Check this box if you had a deposit account(s) at PCSB Bank totaling $100.00 or more on                      , 201     but are not an Eligible Account Holder (“Supplemental Eligible Account Holder”).

Please list all account numbers and all names on accounts you had on these dates in order to insure proper identification of your subscription rights. Failure to list all your eligible accounts, or providing incorrect information, may result in the loss of part or all of your subscription rights.

Community Offering

c. Check this box if you are submitting an order in the community offering and reside in one of the preferred Counties (Indicate County of residence).

d. Check this box if you are submitting an order in the community offering and do not reside in one of the preferred Counties.

Items 7 and 8—Form of Stock Ownership, SS# or Tax ID#, Stock Registration and Mailing Address

Check the box that applies to your requested form of stock ownership and indicate your social security or tax ID number(s) in item 7. Complete the requested stock registration and mailing address in item 8. The stock transfer industry has developed a uniform system of stockholder registrations that will be used in the issuance of your common stock. If you have any questions regarding the registration of your stock, please consult your legal advisor. Stock ownership must be registered in one of the ways described above under “Stock Ownership Guide.” Adding or deleting a name or otherwise altering the form of beneficial ownership of a qualifying account will result in a loss of your subscription rights (with certain exceptions for IRA, Keogh, 401(k) or similar plan purchases).

Item 9 – Telephone Number(s)

Indicate your daytime and evening telephone number(s). We may need to call you if we have any questions regarding your order or we cannot execute your order as given.

Item 10 – Associates/Acting in Concert

Check this box and complete the reverse side of the stock order form if you or any associates or persons acting in concert with you (as defined on the reverse side of the stock order form) have submitted other orders for shares of PCSB Financial Corporation.

Item 11– Acknowledgement

Please review the prospectus carefully before making an investment decision. Sign and date the stock order form where indicated. Before you sign, review the stock order form, including the acknowledgement and certification. Normally, one signature is required. An additional signature is required only when payment is to be made by withdrawal from a deposit account that requires multiple signatures to withdraw funds.

Your properly completed signed stock order form and payment in full (or withdrawal authorization) at the subscription price must be physically received (not postmarked) by PCSB Financial Corporation no later than _:00 p.m., Eastern Time, on              day,                      , 2017 or it will become void. Delivery Instructions: You may deliver your stock order form by mail using the enclosed stock order return envelope or by hand delivery or overnight delivery service to our Stock Information Center. Hand delivered stock order forms will only be accepted at this location. We will not accept stock order forms at our other offices. If you have any additional questions, or if you would like assistance in completing your stock order form, please call our Stock Information Center, Monday through Friday, between the hours of 10:00 a.m. and 4:00 p.m., Eastern Time. The Stock Information Center will be closed on bank holidays.

PCSB Financial Corporation Stock Information Center: 2651 Strang Blvd., Suite 100, Yorktown Heights, NY 10595.

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