12 C.F.R. § 227.15 Unfair late charges.
Title 12 - Banks and Banking
(a) In connection with collecting a debt arising out of an extension of credit to a consumer, it is an unfair act or practice for a bank to levy or collect any delinquency charge on a payment, when the only delinquency is attributable to late fees or delinquency charges assessed on earlier installments, and the payment is otherwise a full payment for the applicable period and is paid on its due date or within an applicable grace period. (b) For the purposes of this section, collecting a debt means any activity, other than the use of judicial process, that is intended to bring about or does bring about repayment of all or part of money due (or alleged to be due) from a consumer.
Title 12: Banks and Banking
PART 227—UNFAIR OR DECEPTIVE ACTS OR PRACTICES (REGULATION AA)
Subpart B—Credit Practices Rule
§ 227.15 Unfair late charges.