27 CFR 25.294: Inventories.

(a) The brewer shall take a physical inventory of beer and cereal beverage at least once each calendar month. The brewer may take this inventory within 7 days of the close of the calendar month for which made.

(b) The brewer shall make a record of inventories of beer or cereal beverage which will show the following:

(1) Date taken;

(2) Quantity of beer and cereal beverage on hand;

(3) Losses, gains, and shortages; and

(4) Signature, under penalties of perjury of the brewer or person taking this inventory.

(c) The brewer shall retain inventory records and make them available for inspection by an appropriate TTB officer.