Interest will be assessed on delinquent payments, to be computed as established, and at the rate in force at the time of said delinquency, by the Federal Social Security Act (42 U.S.C.A. section 301 et. seq.). Such rate shall be applied on a per diem basis based on the number of days from the final due date established for such payment by the Federal Social Security Act through and inclusive of the date such payment is credited to the account of the Secretary of the Treasury of the United States.