22 CFR § 201.25 - Bid and performance bonds and guaranties.
Whenever the importer requires the posting of a bid bond or guaranty or performance bond or guaranty, the type of bond or guaranty (certified check, irrevocable letter of credit, bank bond, bank guaranty, or surety bond) shall be at the option of the bidder or supplier. Posted bid bonds or guaranties shall be returned to unsuccessful bidders promptly after an award is made. Unless converted to a required performance bond or guaranty, any bid bond or guaranty posted by the successful bidder shall also be returned promptly. Performance bonds or guaranties (as distinguished from commodity warranties of quality or performance) shall be canceled no later than 30 days after completion of the contract performance guarantied.