Interest is allowed on most judgements entered in the federal courts from the date of judgment until paid. The types of judgments generally fall under one of three statutes:
28 U.S.C. 1961 (civil and bankruptcy adversary judgment interest);
18 U.S.C 3612 (f)(2) (criminal judgments or sentences);
40 U.S.C 3116 (deficiency judgments in condemnation proceesings).
Under each of the above statutes the rate of interest used in calculating the amount of post judgment interest is the weekly average 1-year constant maturity (nominal) Treasury yield, as published by the Federal Reserve System. Prior to December 21, 2000 the rate of interest allowed under the statutes cited above was based on the coupon issue yield equivalent (as determined by the Secretary of the Treasury) of the average accepted auction price for the last auction of 52 week t- bills settled immediately preceding entry of the judgment. The way the rate is used differs under each of the cited statutes, so those sections should be reviewed to determine how to apply it to any particular judgment.
A thorough discussion of post judgment interest rates from the AOUSC can be found here.
The current interest rate source data is available from the Federal Reserve.
A historical record of weekly Post-Judgment Interest Rates (based on U.S. Treasury securities at 1-year constant maturity) can be found at www.federalreserve.gov.
The current interest rates are located here: Post Judgement Interest Rate