46 USC 40503 – Refunds and waivers
The Federal Maritime Commission, on application of a carrier or shipper, may permit a common carrier or conference to refund a portion of the freight charges collected from a shipper, or to waive collection of a portion of the charges from a shipper, if—
(1) there is an error in a tariff, a failure to publish a new tariff, or an error in quoting a tariff, and the refund or waiver will not result in discrimination among shippers, ports, or carriers;
(2) the common carrier or conference, before filing an application for authority to refund or waive any charges for an error in a tariff or a failure to publish a tariff, has published a new tariff setting forth the rate on which the refund or waiver would be based; and
(3) the application for the refund or waiver is filed with the Commission within 180 days from the date of shipment.