The proprietor must gauge spirits, wine, and alcoholic flavoring materials when required to do so by the appropriate TTB officer or when the spirits, wine, or flavoring materials are:

1. (a) Produced and entered for deposit;
2. (b) Filled into packages from storage tanks;
3. (c) Transferred or received in bond;
4. (d) Transferred between operational accounts;
5. (e) Mixed in the manufacture of a distilled spirits product;
6. (f) Mingled under § 19.329;
7. (g) Reduced in proof before bottling;
8. (h) Voluntarily destroyed;
9. (i) Removed or withdrawn from bond;
10. (j) Tax determined;
11. (k) Returned to bond; or

12. (l) Denatured.

    (26 U.S.C. 5204, 5559)