27 C.F.R. § 28.332
When any claim supported by a bond has been allowed and changed against the bond under the provisions of § 28.331 , and the original of the claim properly executed by the appropriate customs official or armed services officer as required by this part is not received by the appropriate TTB officer within three months of the date the claim was allowed, or where the distilled spirits or wines are not otherwise accounted for in accordance with this part, the appropriate TTB officer shall advise the claimant of the facts, and notify him that unless the original of the claim, properly executed as required by this part, is received by the appropriate TTB officer within 30 days, a written demand will be made upon the principal and the surety for repayment to the United States of the full amount of the drawback, plus interest at the rate prescribed by law from the time the drawback was paid. However, the appropriate TTB officer may, if in his opinion the circumstances warrant it, grant the claimant any additional extension of time beyond 30 days as may be necessary to accomplish the required filing.
27 C.F.R. § 28.332
Sec. 201, Pub. L. 85-859, 72 Stat. 1336 as amended, ( 26 U.S.C. 5062 )