How do I use a credit card to make a payment?

You must specify the amount to be charged to your credit card; the USPTO will not accept a general authorization to charge fees to a credit card. You are strongly advised to use the Credit Card Payment Form (PTO-2038) [PDF] available from the USPTO Forms page. If the credit card number appears on any form or document other than the PTO-2038, the USPTO will not be liable in the event the credit card number becomes public knowledge. (See 37 CFR 1.23(b).)

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USPTO FAQ - Questions and Answers (30MAY2004)