If articles subject to floor stocks tax are stored in a foreign trade zone established under the Foreign Trade Zone Act (the Act of June 18, 1934, 48 Stat. 998, 19 U.S.C. 81a et seq.), the dealer is liable for the tax and must take an inventory in accordance with § 46.207 or when either of the following conditions apply:
(a) Internal revenue taxes have been determined or customs duties liquidated, with respect to the articles pursuant to the first proviso of section 3(a) of the Foreign Trade Zone Act; or
(b) Articles are held by a customs officer pursuant to the second proviso of section 3(a) of the Foreign Trade Zone Act.