16 C.F.R. § 464.2 – Hidden fees prohibited.

(a) It is an unfair and deceptive practice and a violation of this part for any business to offer, display, or advertise any price of a covered good or service without clearly and conspicuously disclosing the total price.
(b) In any offer, display, or advertisement that represents any price of a covered good or service, a business must disclose the total price more prominently than any other pricing information. However, where the final amount of payment for the transaction is displayed, the final amount of payment must be disclosed more prominently than, or as prominently as, the total price.
(c) A business must disclose clearly and conspicuously, before the consumer consents to pay for any covered good or service:
1. (1) The nature, purpose, and amount of any fee or charge imposed on the transaction that has been excluded from total price and the identity of the good or service for which the fee or charge is imposed; and
2. (2) The final amount of payment for the transaction.