Denatured spirits and fuel alcohol are treated as spirits for purposes of this part and are subject to tax pursuant to § 27.40(a). The tax must be paid upon importation, with only two exceptions: Spirits may be withdrawn from customs custody free of tax for the use of the United States under subpart M of this part; and spirits may be withdrawn from customs custody and transferred to a distilled spirits plant, including a bonded alcohol fuel plant, without payment of tax under subpart L of this part. After transfer pursuant to subpart L, denatured spirits or fuel alcohol may be withdrawn free of tax in accordance with part 19 of this chapter if they meet the standards to conform either to a denatured spirits formula specified in part 21 of this chapter (for withdrawal from a regular distilled spirits plant) or a formula specified in § 19.746 of this chapter (for withdrawal from an alcohol fuel plant). Such withdrawal is permitted, even though the denaturation or rendering unfit for beverage use may have occurred, in whole or in part, in a foreign country. For purposes of this chapter, the denaturation or rendering unfit is deemed to have occurred at the distilled spirits plant (including the alcohol fuel plant), the proprietor of which is responsible for compliance with part 21 or § 19.746, as the case may be. Imported fuel alcohol shall also conform to the requirements of 27 CFR 19.742.