27 CFR §20.265

1. (a)Any person required to keep records under this part shall retain copies of invoices which will enable appropriate TTB officers to readily obtain the details regarding:
   1. (1)Purchases of all essential oils, chemicals, and other materials used in manufacturing articles, including the name and address of the vendor, and the quantity;
   2. (2)Purchases of articles containing specially denatured spirits for reprocessing, or purchases of those articles for bottling, repackaging, and/or resale, including the name and address of the vendor and the quantity; and
   3. (3)Dispositions of all articles manufactured or received, including in each case the name and address of the person to whom sold or otherwise disposed of.
2. (b)The appropriate TTB officer may, on application filed by the permittee, waive the requirements for retaining invoices if the quantity sold to any person during a calendar month does not exceed 25 gallons, and if a waiver will not hinder the effective administration of this part and will not pose a jeopardy to the revenue.