Return any unnegotiated checks to your local Social Security office. That office will issue you a receipt for returning any unnegotiated checks. A remittance must be in the form of a check or money order payable to the Social Security Administration. Include the wage earner's Social Security number on the check or money order. Forward the check or money order to your local Social Security office or mail the payment to:

MATPSC
PO Box 3430
Philadelphia PA 19122-9985