National Internal Revenue Code (NIRC)
Section 134. Domestic Denatured Alcohol. - Domestic alcohol of not less than one hundred eighty degrees (180O) proof (ninety percent (90%) absolute alcohol) shall, when suitably denatured and rendered unfit for oral intake, be exempt from the excise tax prescribed in Section 141: Provided, however, That such denatured alcohol shall be subject to tax under Section 106(A) of this Code: Provided, further, That if such alcohol is to be used for motive power, it shall be taxed under Section 148(d) of this Code: Provided, finally, That any alcohol, previously rendered unfit for oral intake after denaturing but subsequently rendered fit or oral intake after undergoing fermentation, dilution, purification, mixture or any other similar process shall be taxed under Section 141 of this Code and such tax shall be paid by the person in possession of such reprocessed spirits.