When applying for a tax stamp using the ATF Form 1 or ATF Form 4, you will have the option to pay with a credit card. The card information is either typed in or hand written on page 3 of the ATF Copy (shown below). But there is no section for the three digit code (security code) that is located on the back or front of the credit card. That is normal. The ATF doesn't require this information when your credit card payment is processed.