Response 12 - Invalid Transaction Explained

Also known as the “invalid transaction” code, a credit card error code 12 is given when the issuing bank does not accept a transaction. That’s super vague, but it’s true. The issuing bank is the bank that gave the customer their card, and a declined 12 code is sort of a catch-all for error codes. It doesn’t mean one specific thing, but there are a few common reasons:


  1. The card number is incorrect. This is the simplest explanation. Sometimes when a card number is typed incorrectly it can fire back an invalid transaction.
  2. The expiration date is invalid. This could mean it was keyed in incorrectly or it’s expired.
  3. AVS failed. Address Verification Service, is a fraud prevention measure implemented by the card member associations such as VISA. They check fields like the zip code against their records to make sure someone isn’t using a card that isn’t theirs.
  4. You tried something strange like refunding a refund. If the system doesn’t know how to handle a request, it could spit back a decline code 12 in response.
  5. The credit card itself is invalid. It’s possible that the card has been canceled or flagged by the credit card company and is coming through as a credit card code 12.
  6. You tried running the card multiple times in a row. Many card associations have measures against multiple quick transactions since it’s often a sign of fraud.

It could be one or a combination of these that is causing your system to fire an invalid transaction. Double-check that it’s not a user error and go from there.