An unmatched transaction is an item left over when two records are compared during reconciliation. It appears on one side, such as a bank statement, processor report or internal ledger, with no counterpart on the other. A credit on the bank statement that the accounting system cannot tie to any invoice or customer is a typical example, as is a payout recorded internally that has not appeared at the bank.
Most unmatched items are caused by timing, missing or altered references, amounts that differ because of fees or currency conversion, or one payment that covers several invoices. Reconciliation software applies matching rules in order of strictness and passes whatever remains to staff, who search for the counterpart or post an adjustment. Unidentified receipts are usually held in a suspense or clearing account until resolved. Each one is a form of reconciliation break, and better payment reference matching is the main way to reduce them.