Except as otherwise provided in this section, the aggregate reduction in the rate of duty on any article which is in effect on any day pursuant to a trade agreement under section 2111 of this title shall not exceed the aggregate reduction which would have been in effect on such day if—

(1) a reduction of 3 percent ad valorem or a reduction of one-tenth of the total reduction, whichever is greater, had taken effect on the effective date of the first reduction proclaimed pursuant to section 2111(a)(2) of this title to carry out such agreement with respect to such article, and

(2) a reduction equal to the amount applicable under paragraph (1) had taken effect at 1-year intervals after the effective date of such first reduction.

If the President determines that such action will simplify the computation of the amount of duty imposed with respect to an article, he may exceed the limitation provided by section 2111(b) of this title or subsection (a) of this section by not more than whichever of the following is lesser:

(1) the difference between the limitation and the next lower whole number, or

(2) one-half of 1 percent ad valorem.

If any part of a reduction takes effect, then any time thereafter during which any part of the reduction is not in effect by reason of legislation of the United States or action thereunder, the effect of which is to maintain or increase the rate of duty on an article, shall be excluded in determining—

(1) No reduction in the rate of duty on any article pursuant to a trade agreement under section 2111 of this title shall take effect more than 10 years after the effective date of the first reduction proclaimed to carry out such trade agreement with respect to such article.

If any part of a reduction takes effect, then any time thereafter during which any part of the reduction is not in effect by reason of legislation of the United States or action thereunder, the effect of which is to maintain or increase the rate of duty on an article, shall be excluded in determining—

(A) the 1-year intervals referred to in subsection (a)(2), and

(B) the expiration of the 10-year period referred to in paragraph (1) of this subsection.

(Pub. L. 93–618, title I, § 109, Jan. 3, 1975, 88 Stat. 1985; Pub. L. 96–39, title XI, § 1106(c)(3), July 26, 1979, 93 Stat. 312.)