What does decline code 51 mean?
Decline code 51 indicates that the cardholder's account does not have sufficient funds to cover the transaction amount. Unlike the generic "Do Not Honor" (code 05), this code provides a clear and specific reason: the available balance is too low.
This is one of the most straightforward decline codes and is commonly encountered in both card-present and card-not-present environments. It applies to debit cards, prepaid cards, and credit cards that have reached their credit limit.
Why this decline happens
The most obvious reason is that the account balance is lower than the transaction amount. However, it is important to understand that the "available balance" may differ from the "current balance" due to pending transactions, holds from hotels or gas stations, or recent deposits that have not yet cleared.
For credit cards, this code means the transaction would push the balance beyond the approved credit limit. Even if the cardholder has made a recent payment, it may not have posted yet, leaving the available credit unchanged.
Recurring subscriptions or automatic payments can also unexpectedly reduce the available balance, leading to declines on subsequent transactions the cardholder attempts.
How to resolve decline code 51
The cardholder should check their account balance through their banking app or by calling their bank. If the issue is pending holds, waiting for them to clear and retrying the transaction is usually sufficient.
Adding funds to the account or making a payment toward the credit card balance will resolve the underlying issue. The cardholder can also try a smaller transaction amount or use an alternative payment method.
For merchants, offering split payment options or alternative payment methods at checkout can help recover sales that would otherwise be lost to insufficient funds declines.
Preventing code 51 declines
Cardholders can set up low-balance alerts through their banking app to stay ahead of potential declines. Enabling overdraft protection or linking a backup funding source can also prevent this code from appearing.
For businesses processing recurring payments, sending payment reminders before charge dates gives customers time to ensure adequate funds are available, reducing failed transaction rates.
