49 U.S. Code § 14705. Limitation on actions by and against carriers
A person must begin a civil action to recover overcharges within 18 months after the claim accrues. If the claim is against a carrier providing transportation subject to jurisdiction under chapter 135 and an election to file a complaint with the Board or Secretary, as applicable, is made under section 14704(c)(1), the complaint must be filed within 3 years after the claim accrues.
The limitation periods under subsection (b) of this section are extended for 6 months from the time written notice is given to the claimant by the carrier of disallowance of any part of the claim specified in the notice if a written claim is given to the carrier within those limitation periods. The limitation periods under subsections (b) and (c) of this section are extended for 90 days from the time the carrier begins a civil action under subsection (a) to recover charges related to the same transportation or service, or collects (without beginning a civil action under that subsection) the charge for that transportation or service if that action is begun or collection is made within the appropriate period.
(f)Government Transportation.—This section applies to transportation for the United States Government. The time limitations under this section are extended, as related to transportation for or on behalf of the United States Government, for 3 years from the later of the date of—
payment of the rate for the transportation or service involved;
deduction made under section 3726 of title 31.