U.S. note 2(v)(xvii)
(xvii) The additional duties imposed by headings 9903.01.25, 9903.01.35, 9903.01.39, 9903.01.63, 9903.02.01–9903.02.73, 9903.02.79–9903.02.80, 9903.02.82–9903.02.83, and 9903.02.87–9903.02.88 shall not apply to the U.S. content of an article, provided at least 20% of the customs value, as determined under 19 U.S.C. 1401a, of the product is U.S. originating, consistent with heading 9903.01.34. For greater certainty, with respect to an article for which at least 20% of the customs value is U.S. originating, consistent with 9903.01.34, the additional duties imposed by headings 9903.01.25, 9903.01.35, 9903.01.39, 9903.01.63, 9903.02.01–9903.02.73, 9903.02.79–9903.02.80, 9903.02.82–9903.02.83, and 9903.02.87–9903.02.88, shall apply only to the non-U.S. content of such article. Heading 9903.01.34 covers only the U.S. content portion of articles described by that heading. The term “U.S. content” refers to the value of an article attributable to the components wholly obtained, produced entirely, or substantially transformed in the United States.