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:
Produced and entered for deposit;
Filled into packages from storage tanks;
Transferred or received in bond;
Transferred between operational accounts;
Mixed in the manufacture of a distilled spirits product;
Mingled under § 19.329;
Reduced in proof before bottling;
Voluntarily destroyed;
Removed or withdrawn from bond;
Tax determined;
Returned to bond; or
Denatured.