26 USC 5006 - Determination of tax

(a) Requirements 

(1) In general 
Except as otherwise provided in this section, the tax on distilled spirits shall be determined when the spirits are withdrawn from bond. Such tax shall be determined by such means as the Secretary shall by regulations prescribe, and with the use of such devices and apparatus (including but not limited to tanks and pipelines) as the Secretary may require. The tax on distilled spirits withdrawn from the bonded premises of a distilled spirits plant shall be determined upon completion of the gauge for determination of tax and before withdrawal from bonded premises, under such regulations as the Secretary shall prescribe.
(2) Distilled spirits not accounted for 
If the Secretary finds that the distiller has not accounted for all the distilled spirits produced by him, he shall, from all the evidence he can obtain, determine what quantity of distilled spirits was actually produced by such distiller, and an assessment shall be made for the difference between the quantity reported and the quantity shown to have been actually produced at the rate of tax imposed by law for every proof gallon.
(b) Taxable loss 

(1) On original quantity 
Where there is evidence satisfactory to the Secretary that there has been any loss of distilled spirits from any cask or other package deposited on bonded premises, other than a loss which by reason of section 5008 (a) is not taxable, the Secretary may require the withdrawal from bonded premises of such distilled spirits, and direct the officer designated by him to collect the tax accrued on the original quantity of distilled spirits entered for deposit on bonded premises in such cask or package; except that, under regulations prescribed by the Secretary, when the extent of any loss from causes other than theft or unauthorized voluntary destruction can be established by the proprietor to the satisfaction of the Secretary an allowance of the tax on the loss so established may be credited against the tax on the original quantity. If such tax is not paid on demand it shall be assessed and collected as other taxes are assessed and collected.
(2) Alternative method 
Where there is evidence satisfactory to the Secretary that there has been access, other than is authorized by law, to the contents of casks or packages stored on bonded premises, and the extent of such access is such as to evidence a lack of due diligence or a failure to employ necessary and effective controls on the part of the proprietor, the Secretary (in lieu of requiring the casks or packages to which such access has been had to be withdrawn and tax paid on the original quantity of distilled spirits entered for deposit on bonded premises in such casks or packages as provided in paragraph (1)) may assess an amount equal to the tax on 5 proof gallons of distilled spirits at the prevailing rate on each of the total number of such casks or packages as determined by him.
(3) Application of subsection 
The provisions of this subsection shall apply to distilled spirits which are filled into casks or packages, as authorized by law, after entry and deposit on bonded premises, whether by recasking, filling from storage tanks, consolidation of packages, or otherwise; and the quantity filled into such casks or packages shall be deemed to be the original quantity for the purpose of this subsection, in the case of loss from such casks or packages.
(c) Distilled spirits not bonded 

(1) General 
The tax on any distilled spirits, removed from the place where they were distilled and (except as otherwise provided by law) not deposited in storage on bonded premises of a distilled spirits plant, shall, at any time within the period of limitation provided in section 6501, when knowledge of such fact is obtained by the Secretary, be assessed on the distiller of such distilled spirits (or other person liable for the tax) and payment of such tax immediately demanded and, on the neglect or refusal of payment, the Secretary shall proceed to collect the same by distraint. This paragraph shall not exclude any other remedy or proceeding provided by law.
(2) Production at other than qualified plants 
Except as otherwise provided by law, the tax on any distilled spirits produced in the United States at any place other than a qualified distilled spirits plant shall be due and payable immediately upon production.
(d) Unlawfully imported distilled spirits 
Distilled spirits smuggled or brought into the United States unlawfully shall, for purposes of this chapter, be held to be imported into the United States, and the internal revenue tax shall be due and payable at the time of such importation.
(e) Cross reference 
For provisions relating to removal of distilled spirits from bonded premises on determination of tax, see section 5213.