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

Except 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. No 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.