27 C.F.R. § 19.461 – Losses and shortages in general.

(a) Allowable losses and shortages. Except as otherwise provided in paragraph (b) of this section, TTB will not collect tax on spirits, denatured spirits, or wines that are lost, destroyed, or otherwise unaccounted for while in bond, and if the tax has already been paid, TTB will refund the tax.
(b) Exceptions. TTB will collect the tax in the case of:
1. (1) Theft, unless the appropriate TTB officer finds that the theft occurred without connivance, collusion, fraud or negligence on the part of the proprietor, owner, consignor, consignee, bailee, or carrier, or any employee or agent of any of them;
2. (2) Voluntary destruction carried out other than as provided in subpart Q of this part;
3. (3) An unexplained shortage of bottled spirits.
(c) Burden of proof. When it appears that a theft occurred, the burden of proof will be on the proprietor or other person liable for the tax to establish to the satisfaction of the appropriate TTB officer that the theft did not result from connivance, collusion, fraud, or negligence on the part of the proprietor, owner, consignor, consignee, bailee, or carrier, or any employee or agent of any of them.
(d) Claims. Claims for losses and shortages allowable under this section must be filed in accordance with the provisions of subpart J of this part.
(e) Limitations. TTB will abate, remit, credit, or refund taxes on spirits, denatured spirits, or wines lost by theft only to the extent that the claimant is not indemnified against, or recompensed for, the taxes paid or owed.
(26 U.S.C. 5008, 5370)