ACH vs wire transfer for AP: choose by deadline, amount, and error risk
Compare ACH and wire transfers by delivery deadline, bank fees, payment finality, amount limits, and the cost of correcting an error.
Bottom line
Use ACH for scheduled U.S. supplier payments when the business can plan around bank processing windows. Use a wire when same-day final settlement, a high-value deadline, or a closing condition justifies the higher bank fee and stricter error controls. Neither rail makes bad bank details safe.
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- Write down the supplier deadline and the last acceptable arrival time
- Confirm the bank or platform fee for the selected rail
- Check the bank and platform limit before approving a large payment
- Verify new or changed bank instructions through a trusted second channel
- Record who may request a reversal, recall, or payment trace
- Send the supplier an invoice-level payment reference
The deadline should decide the rail
Start with the time when the supplier must have usable funds, then work backward through bank cutoffs, weekends, holidays, internal approval, and any platform review. A due date in the AP system is not the same as a guaranteed receipt time.
Nacha says ACH credits can settle on the same banking day or on a later banking day, depending on how the payment is submitted. Fedwire processes accepted transfers individually in real time and provides final settlement between participating institutions [Nacha, 2026; Federal Reserve Financial Services, 2026].
Compare the dimensions that change the decision
| Decision dimension | ACH | Wire transfer |
|---|---|---|
| Common AP fit | Scheduled domestic invoices and payment batches | Time-critical or high-consequence payments |
| Speed | Same-day or later settlement, subject to eligibility and cutoffs | Real-time processing after an accepted Fedwire order, subject to the sending bank |
| Cost | Often lower, but the bank or platform sets the customer fee | Often higher, and intermediary or receiving-bank charges may apply |
| Error recovery | Nacha permits reversals only for defined errors and within its rules | Fedwire settlement is final and irrevocable between participants; a customer recall is not a guaranteed undo button |
| Amount limits | Same Day ACH is capped at $1 million per payment through September 16, 2027 | The bank and payment platform set customer limits and approval rules |
The scheduled increase of the Same Day ACH cap to $10 million takes effect September 17, 2027. A business should not split a payment to evade a network or provider limit [Nacha, 2026].
A mistaken ACH is not freely reversible
Nacha lists narrow reasons for a reversing entry, including a duplicate, an incorrect receiver, an incorrect amount, and certain date errors. The originating party must also meet timing and formatting rules. A change of mind or a funding problem is not a valid reason to reverse an ACH credit [Nacha, 2026].
A wire needs even more caution before release. Fedwire settlement is final between participating institutions once the receiving participant is credited. A bank may try to recall funds after a customer error, but AP should treat that as recovery work, not as a control [Federal Reserve Financial Services, 2026].
The largest risk sits before the payment
Business email compromise turns a routine vendor update into a payment loss. Require a call to a known contact for new or changed routing instructions. Do not use the phone number in the change request itself.
Large and urgent payments should have a second approver who sees the supplier name, destination account, amount, invoice support, deadline, and selected rail. Urgency changes the review order. It does not remove the review.
Where Melio fits in the workflow
Melio lets a payer select a funding method and a vendor delivery method. Its help center distinguishes ACH routing details from domestic wire routing details and shows an estimated delivery date during scheduling [Melio, 2025].
Use the estimate to plan the payment, then keep the invoice number or vendor memo with the transaction. Fees, delivery choices, eligibility, and limits can vary by account and payment, so the approver should check the live confirmation screen before release.
Frequently asked questions
Is ACH always slower than a wire? No. Same Day ACH can settle on the same banking day, but eligibility, submission windows, bank processing, and provider cutoffs still matter.
Is a wire safer because it is final? Finality reduces settlement uncertainty after a correct transfer. It increases the cost of sending money to the wrong account.
Can AP reverse an ACH whenever a supplier dispute appears? No. Nacha limits reversals to defined processing errors. A commercial dispute needs a separate resolution.
What amount requires a wire? There is no universal customer threshold. Check the applicable ACH network rule, bank limit, platform limit, and the payment contract.
What should appear in the approval record? Keep the invoice, due date, amount, supplier verification, selected rail, fee, approvers, confirmation number, and remittance reference.