27 CFR §20.252

1. (a)General. The appropriate TTB officer may waive the requirement to obtain a permit under subpart D of this part if a nonpermittee can demonstrate that more than five gallons is necessary to determine if an Industrial Use Permit is desired.
2. (b)Application. A nonpermittee who wishes to obtain more than five gallons of specially denatured spirits to determine if an Industrial Use Permit is desired, shall file a letterhead application with the appropriate TTB officer in which the nonpermittee's premises are located. The letter shall describe why the requested quantity is necessary.
3. (c)Approval. If the letterhead application is approved, the nonpermittee shall submit it to the proprietor of a distilled spirits plant or a dealer with the order for the sample of specially denatured spirits.