A vendor ACH authorization form is the document you give a client so they can pay your invoices by direct deposit instead of mailing checks. You fill in your legal business name and tax ID, your bank’s routing and account numbers, and an authorized signature, then return the form with a voided check or bank letter to the client’s accounts payable team. Once they verify the account, future payments land in your bank account on whatever terms you’ve already agreed to.
The form itself is short. Getting it right the first time is what matters, because almost every mistake on an ACH setup costs you one to two weeks while someone emails back asking for a corrected version.
What to Gather First
Three things need to be sitting in front of you before you start typing: your tax details, your bank details, and a document from your bank that independently confirms those account numbers.
Tax and Business Information
Your legal business name has to match the name on your tax filings exactly. That same name appears on IRS Form W-9, which the client will almost certainly ask for alongside the ACH form so they can report payments on a 1099. If the Taxpayer Identification Number you provide doesn’t match IRS records, the client is required to withhold 24 percent of every payment as backup withholding until the mismatch is fixed.1Internal Revenue Service. Instructions for the Requester of Form W-9 That money sits with the IRS until you file your return, so verify the name and number carefully.
Most businesses use their nine-digit Employer Identification Number. Sole proprietors without an EIN use their Social Security Number. You’ll also need your physical mailing address and a contact in your accounts receivable department the client can reach if a payment fails.
Banking Information
From your bank, pull three items: the bank’s name, the nine-digit routing transit number, and your account number. The form will ask whether the account is checking or savings, because the ACH network treats them differently. The routing number appears at the bottom left of any check, and most banks also display both numbers in the online banking portal or mobile app.2Nacha. Direct Deposit Without a Voided Check? Absolutely! If neither is handy, call the bank.
Proof of the Account
Nearly every client requires a document that independently confirms the routing and account numbers. The two usual options:
- A voided check. Write “VOID” in large letters across the face in permanent ink, without covering the routing or account numbers along the bottom edge.
- A bank verification letter on official letterhead listing the account holder’s name, account number, and routing number. Many banks generate these instantly through online banking.2Nacha. Direct Deposit Without a Voided Check? Absolutely!
One trap catches a lot of first-time setups: the name on the bank account has to match the legal name on the form. If the authorization says “Smith Consulting LLC” and the bank account is in the name of “John Smith,” the receiving bank can’t match the incoming deposit to an account holder and sends the whole transaction back. Fix the mismatch before you submit, not after.
Completing Each Section
Forms vary from company to company. Some clients send a fillable PDF; others route you through a vendor portal. The fields fall into the same four groups either way.
Company and Contact
Legal business name, any DBA name, street address, city, state, ZIP code. A line for the accounts receivable contact with phone and email. Fill in every field, even the ones that feel redundant. Blank fields create follow-up emails, and follow-up emails cost you days.
Banking
Bank name, routing number, account number, account type. Some forms also ask for the bank’s address or phone number. Check every digit against your voided check or bank letter. A single transposed number can trigger an ACH return and bounce the whole setup back to the start.
The Authorization Language
There will be a paragraph of legal text authorizing the client to send electronic credits to your account. Read it. Almost every version also lets the client initiate a reversing debit to pull back a payment that was erroneous or duplicated. Nacha rules require any such reversal to be transmitted within five banking days of the original payment’s settlement.3Nacha. ACH Network Rules – Reversals and Enforcement If the language goes beyond that and tries to give the client open-ended debit authority over your account, push back before you sign. A vendor authorization should permit credits in, plus corrections for overpayments, and nothing more.
Signature
The signer needs authority to bind the company to financial agreements. In practice that means an owner, CFO, treasurer, or controller. Print the signer’s name, add a title, and date it. Unsigned, undated, or wrong-signer forms get kicked back by the client’s compliance team, and you start over.
Sending the Form Securely
The completed form holds your bank account number, routing number, and tax ID in one place. Treat it like a live check. Options that are acceptable:
- A password-protected PDF by email, with the password shared separately by phone or text.
- Upload through the client’s secure vendor portal, if they run one.
- Certified or registered mail, envelope marked “Confidential.”
- Secure fax, which is still common in industries that haven’t fully digitized accounts payable.
Nacha’s rules require large originators (those processing more than two million ACH entries a year) to render stored account numbers unreadable through encryption or similar methods.4Nacha. Supplementing Data Security Requirements A big corporate client’s vendor portal almost certainly meets that bar. If someone on their team asks you to email the form as a plain attachment, raise it before you comply.
What Happens After You Send It
Expect a quiet week or two between submitting the form and seeing your first electronic payment. Two verification methods are standard.
Prenote. The client sends a zero-dollar test transaction through the ACH network to confirm the routing number, account number, and account type are valid. Nacha rules require them to wait at least three banking days after the prenote settles before originating a live payment. Many companies wait longer out of caution, so the total window from form submission to first live deposit usually runs one to two weeks.
Micro-deposits. Some clients send two small credits, usually under a dollar each, and ask you to confirm the exact amounts. Watch your bank activity in the days after you submit the form so you can respond quickly when the request arrives.
While verification is in progress, the client will typically keep paying outstanding invoices by check. A gap doesn’t mean something went wrong. Once the ACH link is live, payments shift to electronic deposit on the schedule in your contract, whether that’s net 30, net 60, or something else.
One boundary worth knowing: if your bank account is held at a foreign institution or the funds route through one, the payment becomes an International ACH Transaction and triggers extra screening against the OFAC sanctions list.5American Bankers Association. NACHA International ACH Transaction Rule For a domestic vendor paid from a domestic client, this doesn’t come up.
Changing or Canceling the Authorization
If you switch banks, open a new account, or want to stop ACH payments from a particular client, revoke or update the authorization in writing. Send a signed notice to accounts payable with an effective date, and give enough lead time (two to three weeks is reasonable) for them to process the change before the next payment cycle.
Revoking the ACH authorization doesn’t cancel the underlying contract or any unpaid invoices. It just moves the payment method back to checks or another arrangement. If you’re moving to a new bank account rather than stopping payments entirely, submit a new authorization with the updated banking details at the same time as the revocation. Leaving two active authorizations in the system invites a misdirected payment.
If a Payment Goes Wrong
If the client sends a duplicate payment or the wrong amount, the reversing-entry provision in the form gives them five banking days to correct it.3Nacha. ACH Network Rules – Reversals and Enforcement If you spot an incorrect deposit, call accounts payable before you spend or move the funds. Cooperation is faster and cleaner than a formal ACH dispute through the banking system.
Business ACH disputes run under UCC Article 4A, which governs commercial funds transfers. Liability for an unauthorized payment can shift to you if your bank offered a commercially reasonable security procedure and you declined it or failed to follow it. That’s a reason to take your bank’s dual-authorization settings, fraud alerts, and online security features seriously, because they feed into who bears the loss when something goes wrong.
Records to Keep
Hold onto a copy of every signed authorization, the voided check or bank letter you submitted with it, and any correspondence about the setup. The IRS requires taxpayers to maintain records sufficient to support the figures on their returns, and electronic payment records fall under that requirement.6Internal Revenue Service. Rev. Proc. 98-25 A retention period that matches your general recordkeeping policy, typically at least three years after the tax year the payments relate to, covers most businesses. If you store these records with a third-party service, the obligation to produce them on request still sits with you.