The Postal Service™ periodically publishes the interest rate payable on a claim decided in a supplier‘s favor under the Contract Disputes Act of 1978 in the Postal Bulletin. This rate also applies for late payments to suppliers under the Prompt Payment Act, as amended.
The interest rate effective for the 6-month period of July 1 to December 31, 2019, is 2.625 percent.
— Supply Management Infrastructure, Supply Management, 7-4-19
USPS.com
