41 C.F.R. § 102-118.200

A claim must be received by the agency where the claim arose within 3 years beginning the day after the latest of the following dates (except in time of war)—

(a) Accrual of the cause of action;

(b) Payment of charges for the transportation involved;

(c) Subsequent refund for overpayment of those charges; or

(d) Deductions made to a TSP claim by the Government under 31 U.S.C. 3726.