What ACH account verification is
Before a business sends money to a bank account, or collects money from one, it helps to know that the account is real. A wrong digit sends the payment back. A stolen account number can end in an unauthorized debit.
ACH account verification is any check that happens before the first payment. Nacha, the organization that writes the ACH rules, calls it account validation. It says account validation is a best practice for all organizations sending payments, for credits and for debits.
The ways to verify an account
| Method | How it works | Speed | What it proves | When the rules ask for it |
|---|---|---|---|---|
| Routing number check | Tests the 9 digits against the checksum | Instant. Use the routing number checker | The routing number is correctly formed. It does not check the account | The rules do not ask for it |
| Prenote | Zero-dollar test entry | The third banking day after it settles | If nothing comes back, the account is open and can take ACH payments | One way to meet the rule for online debits. Optional for other payments |
| Micro-entries | One or more small deposits of under $1 each that the account holder confirms. They carry the description ACCTVERIFY | As soon as the person reports the amounts | The account can be paid into, and the person can see the account | One way to meet the rule for online debits. Optional for other payments |
| Validation service | A commercial service that checks the account for you | Set by the service | It varies. Ask whether it checks only that the account is open, or also who owns it | One way to meet the rule for online debits. Optional for other payments |
| Voided check or bank letter | Shows the numbers as the bank prints them | When you receive it | The numbers, as the bank prints them | The rules do not ask for it |
“The rule for online debits” is explained in the next section.
Micro-entries have one advantage over a prenote. The account holder has to report the amounts, which shows they can see the account. A prenote only shows that the account exists.
When the ACH rules ask for a check
Nacha’s public rule pages name one kind of payment for which account validation is required.
- Which payments. Consumer debits that are authorized or started online. The ACH rules call these WEB debits.
- Since when. March 19, 2021.
- When. The first time an account number is used, and when the account number changes.
Nacha answers the common questions about the rule on its own page.
| Question | Nacha’s answer |
|---|---|
| What does “validate” mean? | At a minimum, find out that the account is a legitimate, open account to which ACH entries may be posted |
| Must the business also check who owns the account? | No. For some businesses a stricter check that also verifies ownership may be appropriate |
| Is one method required? | No. The rule is “neutral regarding specific methods or technologies” |
| Which methods does Nacha give as examples? | A prenote, micro-entries, and a commercial validation service from a bank or another company |
| Do existing customers have to be checked again? | No. The rule applies to new account numbers. An account number with a history of successful payments counts as validated |
| What if the bank sends a corrected account number in a Notification of Change (NOC)? | The business need not validate the corrected number again, if it applies the change correctly |
For other kinds of ACH payment, Nacha calls account validation a best practice, and it says prenotes are optional for every payment type. Why the check is still worth doing is in ACH fraud prevention.
How micro-deposits work
Micro-deposits are small test payments. The ACH rules call them Micro-Entries.
- The business sends one or more small credits. Each one must be less than $1.
- It may take the money back. If it sends debits to offset the credits, it must send them at the same time, and the debits together must not be more than the credits. The account must never end up with less money.
- The description reads ACCTVERIFY. The company name must be one the account holder will recognize, and the same as or similar to the name on later payments.
- The account holder confirms the amounts to the business.
- Only then can real payments start. A real payment must not be sent at the same time as the micro-entries.
Two points are easy to miss.
- Silence is not a yes. Nacha says that if the account holder never confirms the amounts, the business cannot treat the account as verified, even when the bank did not return the micro-entries.
- The business must watch for misuse. Since March 17, 2023, a business that sends micro-entries must use commercially reasonable fraud detection, including watching how many it sends and how many come back.
The Micro-Entry rule itself took effect on September 16, 2022.
A provider sets its own time limit for the customer. Stripe’s page, checked on October 2, 2026, says customers have 10 days to verify a bank account with micro-deposits. That is one company’s rule, not a rule of the network.
How a prenote verifies an account
A prenote is a zero-dollar test entry. The receiving bank answers only if something is wrong, with a return or a Notification of Change. Nacha says that when no answer comes by the end of the return period, the business can treat the account as open and able to accept ACH entries.
You can send the first real payment on the third banking day after the prenote settles. The full steps and the transaction codes are in the ACH prenote guide.
What verification does not prove
- The name. A prenote checks the account number. A bank guide for businesses says the receiving bank is not required to check the name on a prenote.
- Who owns the account. The minimum in the Nacha rule is that the account is open. A validation service may check more. Ask it.
- That the customer agreed to the payment. Verification is not authorization. To collect money you still need the customer’s authorization. See the ACH authorization form.
- That a payment will go through. An account can be open and still not have enough money. See R01.
Choosing a method
| Your situation | A method that fits |
|---|---|
| You take debits that customers authorize online | Account validation is needed the first time you use an account number. A prenote, micro-entries and a validation service are the examples Nacha gives |
| A new employee’s first direct deposit, with payday more than a few days away | A prenote |
| You want to know the person can see the account | Micro-entries |
| A payment must go out today | A routing number check and a careful read of the account number. A validation service, if you have one |
| You only have numbers typed into an email | Ask for a voided check or a bank letter, and confirm any change by phone |
Your bank or processor may charge for a prenote, for micro-entries or for a validation service. Ask for its price list.
Common mistakes
- Treating a routing number check as account verification. It tests the 9 digits. It cannot say that an account exists.
- Sending the real payment before the micro-deposits are confirmed. The business must wait for the account holder’s answer.
- Sending the real payment too soon after a prenote. Wait until the third banking day after the prenote settles.
- Assuming verification checked the name. A prenote checks the account number. The bank does not have to check the name.
- Skipping the check for online debits. Since March 19, 2021 it is part of the rules for those payments.