On receipt of the executed Form 5620.7 from the district director of customs, the appropriate TTB officer will allow or disallow the claim in accordance with existing law and regulations. If the claim is not allowed in full the appropriate TTB officer will notify the claimant, in writing, of the reasons for any disallowance.
27 C.F.R. § 44.232
72 Stat. 1419; 26 U.S.C. 5706