Abstract: A method for preventing unauthorized use of credit cards in remote payments and a supplemental-code card for therein is disclosed. A unique code list is provided by the credit company to the credit card owner for use with the credit card. The codes are distributed in a variety of possible ways, including through A.T.M. machines, stores, e-mail or faxes. A copy of each code list is associated at the credit card company with the owner of the credit card. Each code is only for a single use. For every remote payment, the credit card owner transmits one of the codes to the creditor, along with conventional credit card data. The credit card company verifies the transmitted information and accepts or rejects the transaction. The codes may be provided on a supplemental-code card with some mechanism to ensure that each code is used only once.