27 CFR § 19.613 - Average effective tax rate records.
(1) The serial number of the batch record of each batch of the product that will be bottled or packaged, in whole or in part, for domestic consumption;
(3) The tax liability of each such batch determined as follows -
(iii) Proof gallons of all distilled spirits derived from eligible flavors, to the extent that those distilled spirits exceed 2.5 percent of the proof gallons in the product, multiplied by the tax rate prescribed in 26 U.S.C. 5001.
(b) Monthly records. At the end of each month during which the product is manufactured, the proprietor must:
(2) Add the sums derived under paragraph (b)(1) of this section to the like sums determined for each of the preceding 5 months; and
(3) Divide the total tax liabilities by the total proof gallons.
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