ACH Error R51 - What is this?

ACH code R51 refers to “Not sufficient funds” or “NSF” and indicates that a transaction was returned unpaid due to insufficient funds in the account. This can happen when a person or business tries to withdraw money from an arrangement that does not have enough funds to cover the transaction.
When an ACH transaction is processed, and the account does not have enough funds to cover it, the bank will typically return the transaction and charge the account holder an NSF fee. The bank that initiated the transaction will also likely charge a fee for the returned transaction.
It is crucial to ensure sufficient funds in an account before initiating ACH transactions to avoid incurring NSF fees and returned transactions. If you receive an ACH code R51 notification, you should contact your bank to understand why the transaction was returned and take steps to remedy the situation.