provided for under article 5.16 of the USMCA shall be prescribed not later than the date on which the USMCA enters into force. (3) Implementing actions with effective dates after entry into force In the case of any implementing action that takes effect on a date after the date on which the USMCA enters into force, initial regulations to carry out that action shall, to the maximum extent feasible, be prescribed within 1 year after such effective date. (c) Tariff modifications (1) Tariff modifications provided for in the USMCA The President may proclaim— (A) such modifications or continuation of any duty, (B) such continuation of duty-free or excise treatment, or (C) such additional duties, as the President determines to be necessary or appropriate to carry out or apply articles 2.4, 2.5, 2.7, 2.8, 2.9, 2.10, 6.2, and 6.3, the Schedule of the United States to Annex 2–B, including the appendices to that Annex, Annex 2–C, and Annex 6–A, of the USMCA. (2) Other tariff modifications Subject to the consultation and layover provisions of section 104, the President may proclaim— (A) such modifications or continuation of any duty, (B) such modifications as the United States may agree to with a USMCA country regarding the staging of any duty treatment set forth in the Schedule of the United States to Annex 2–B of the USMCA, including the appendices to that Annex, (C) such continuation of duty-free or excise treatment, or (D) such additional duties, as the President determines to be necessary or appropriate to maintain the general level of reciprocal and mutually advantageous concessions with respect to a USMCA country provided for by the USMCA. (3) Conversion to ad valorem rates For purposes of paragraphs (1) and (2), with respect to any good for which the base rate in the Schedule of the United States to Annex 2–B of the USMCA is a specific or compound rate of duty, the President shall substitute for the base rate an ad valorem rate that the President determines to be equivalent to the base rate. (4) Tariff-rate quotas In