NACHA defines over 80 ACH return codes, but most businesses only run into a handful of them. R01 (insufficient funds), R02 (account closed), R03 (no account found), and R04 (invalid account number) account for the vast majority of returns. You can look up any code and what to do about it on this page.

The receiving bank (RDFI) issues the return code. When an ACH transaction fails, the bank that holds the recipient's account sends a return code back through the ACH network explaining why. Nickel surfaces the code and the reason in your dashboard so you can see exactly what happened without calling your bank.

It depends on the code. Most returns are sent within 2 banking days of the original transaction. For unauthorized transactions (like R07 or R10), the customer's bank has up to 60 calendar days to return it. On your end, there's no formal deadline to "respond," but the sooner you address the issue (contact the customer, correct the account number, or resubmit), the sooner you get paid.

Yes, for most return codes. If a payment comes back as R01 (insufficient funds), you can resubmit it after the issue is resolved. NACHA rules generally allow up to 2 retries within 180 days of the original return. Some codes (like R02, account closed, or R04, invalid account number) can't be retried until the underlying issue is fixed. Nickel shows you the return reason so you know whether to retry or reach out to the customer first.

The most common returns are caused by insufficient funds, closed accounts, and incorrect bank info. You can reduce them by verifying account and routing numbers before the first transaction (Nickel does this automatically), sending payment reminders before the charge date so customers know it's coming, and using recurring invoices with stored payment methods so the same verified account is charged each time. Nickel doesn't charge you a fee for ACH returns.