A prenote, short for prenotification entry, is a zero-dollar ACH entry you send to a bank account before the first real payment or debit. It travels through the ACH network like any other entry. If the routing number or account number is wrong, the receiving bank sends it back or sends a notification of change. If nothing comes back, you proceed. It is optional under the Nacha rules, it costs a few days, and it is the cheapest way to find out that a new employee or vendor gave you the wrong account number.
Nacha rule references below were read from nacha.org on 2026-10-29.
What a prenote is
A prenote is an ordinary entry detail record with an amount of zero and one of four transaction codes:
| Account type | Credit prenote | Debit prenote |
|---|---|---|
| Checking | 23 | 28 |
| Savings | 33 | 38 |
Everything else about the record is the same as the live entry you plan to send: the same routing number, account number, receiver name and company details. That is the point. The prenote exercises exactly the path the money will take.
What happens after you send one
The receiving bank gets the prenote in the normal file from its ACH operator and checks whether the account exists as described.
- If the account number or routing number is wrong, the bank returns the prenote with a return reason such as R03 (no account) or R04 (invalid account number).
- If the account exists but a detail is off, such as an account that moved from checking to savings or a routing number that changed in a merger, the bank sends a notification of change (a NOC) with the corrected detail. You must update your records before the next entry.
- If nothing comes back, the account is treated as valid and you send the live entry.
Under the Nacha rules the originator waits three banking days after sending the prenote before initiating live entries. Nacha's own ACH developer guide puts it as "at least three business days prior to initiating a live authorized Entry". Count banking days, not calendar days: a prenote sent on Thursday clears the waiting period the following Tuesday if there is no holiday.
What a prenote cannot tell you
A prenote confirms that an account exists at that routing number and accepts entries. It does not confirm that the account belongs to the person named on it, that it has funds, or that the person has authorized you to debit it. A silent prenote is not proof of ownership. Those checks need a different method: a signed authorization, a micro-deposit confirmation, or a commercial account validation service.
When to send one
- A new employee's direct deposit. A prenote in the onboarding week means payday one does not bounce. The payroll use case builds this into the setup steps.
- A new vendor you will pay by ACH. Especially when the bank details arrived by email, where a mistyped digit and a fraudulent change request look the same.
- Changed account details. Nacha's developer guide recommends a prenote whenever an account number or financial institution changes. Since June 21, 2024, the rules also allow prenotes for re-validating an account you have paid before, not only before the first entry.
- The first WEB debit from a consumer. Nacha's account validation rule for WEB debits requires a commercially reasonable check that the account number is valid before the first debit, and Nacha lists a prenote as one acceptable method.
When you can skip it
- The account was validated another way: a micro-deposit the receiver confirmed, or a validation service.
- The payment cannot wait three banking days and you accept the risk of a return.
- You have paid the account recently and nothing has changed.
A prenote is a trade of a few days for certainty about the account number. For a one-off payment to a known account, the trade is often not worth it. For anything recurring, it almost always is.
Sending a prenote from FiSTWorks
In ACH Drafter, tick the prenote checkbox when you create a batch. Every entry in that batch is written with a zero amount and the matching prenote transaction code, the entry description defaults to PRENOTE, and everything else works as it does for a live batch. When the waiting period has passed, create the live batch from the same recipients. If you import a file that mixes prenote and live entries, the importer splits them into separate batches and reminds you of the waiting period. The Drafter guide has the steps, and the NOC code reference explains what to change when a notification comes back.
Sources
- Nacha, ACH File Overview, ACH Guide for Developers, read 2026-10-29.
- Nacha, Request for Information: Definition of Banking Day and Related Operational Topics, read 2026-10-29.
- Nacha, Minor Rules Topics (prenotification changes effective June 21, 2024), read 2026-10-29.
- Nacha, Account Validation FAQs, read 2026-10-29.