15 U.S.C. § 1666i–2: Additional limits on interest rate increases

(a) Limitation on increases within first yearExcept in the case of an increase described in paragraph (1), (2), (3), or (4) of section 1666i–1(b) of this title, no increase in any annual percentage rate, fee, or finance charge on any credit card account under an open end consumer credit plan shall be effective before the end of the 1-year period beginning on the date on which the account is opened. (b) Promotional rate minimum termNo increase in any annual percentage rate applicable to a credit card account under an open end consumer credit plan that is a promotional rate (as that term is defined by the Bureau) shall be effective before the end of the 6-month period beginning on the date on which the promotional rate takes effect, subject to such reasonable exceptions as the Bureau may establish, by rule.