What to do when a customer pays multiple invoices in one ACH

Capture the posted date, amount, originator name, company ID, trace or transaction ID, entry description, and addenda text that your bank provides. Bank interfaces may truncate the visible row, so use the export or detail view when possible.

Preserve that source text. A cleaned name helps matching, but the raw company ID or trace value may be the best evidence later.

Search the ACH addenda, customer email, remittance portal, or shared AR inbox for invoice references. If remittance arrives separately, connect it to the payment through a stable transaction or customer reference.

Do not rely on an emailed spreadsheet without checking that its total equals the posted ACH and that the invoice balances were open for the stated amount.

Load the referenced invoices and total their current outstanding balances. If the sum equals the ACH, verify customer, currency, date, and duplicates before confirmation.

If the total differs, identify whether the remittance includes a partial, credit, deduction, or invoice that has already been paid. Keep the difference explicit while investigating.

Use the payer-to-customer mapping and compatible currency to build a small set of open invoices. Search combinations within reasonable count and size limits. A mathematical total without identity support stays in review.

Contact the customer for remittance advice if several plausible combinations remain. Recording the follow-up is better than forcing an allocation that will need to be reversed.

Apply the ACH to each confirmed invoice, preserve any partial or unapplied amount, and record the reviewer and evidence. Verify the accounting system after posting or import.

If the payer name is recurring, save an explicit workspace-level alias. Keep it editable so a later entity change does not become opaque matching behavior.