Answer
A remittance advice tells the supplier which invoices a payment covers—listing invoice numbers, amounts, deductions, and credits applied. It helps the supplier's AR team apply the cash correctly and reduces unapplied-cash and reconciliation queries. It can be emailed, sent via EDI, or delivered through a portal.
Real-world example A single ACH payment covering ten invoices includes a remittance so the supplier can match each invoice and clear its ledger.