5 CFR §831.2106

1. (a)The agency, Clerk of the House of Representatives, or Secretary of the Senate shall have the employee or Member:
   1. (1)Complete an application to make deposit;
   2. (2)Provide a copy of his or her DD 214 or its equivalent to verify the period(s) of service; and
   3. (3)Provide sufficient evidence of basic pay, if available, or a statement of estimated earnings.
2. (b)Upon receipt of the application, the DD 214(s), and either sufficient evidence of basic pay, if available, or a statement of estimated earnings, the agency, Clerk of the House of Representatives, or Secretary of the Senate shall multiply the amount of basic pay by 7 percent to compute the exact deposit owed, exclusive of any interest.
3. (c)If interest is applicable, it shall be computed in accordance with instructions published by OPM.
4. (d)The agency, Clerk of the House of Representatives, or Secretary of the Senate shall establish a deposit account showing the total amount due, and a payment schedule (unless deposit is made in a lump sum), and record the date and amount of each payment.
5. (e)An individual who is eligible to make deposit to OPM shall submit an application to make deposit, accompanied by a copy of his or her DD 214(s) or its (their) equivalent(s), as well as sufficient evidence of basic pay, if available, or a statement of estimated earnings, to OPM.