Dual-Message Processing

Dual-message processing is a two-step process. The authorization is processed first. If the authorization is successful, the capture is processed immediately afterward. The response includes the authorization and the capture information. If the authorization is declined, the capture is not processed, and the response message includes only the authorization information.

Partial Authorizations

All debit and prepaid card processors as well as a limited number of credit card processors support partial authorizations when dual-message processing is in place.
When partial authorization is enabled, the issuing financial institution can approve a partial amount when the balance on the card is less than the requested amount. When a partial amount is authorized, the capture is not processed. The merchant can then use a second card to cover the balance, adjust the total cost, or void the transaction.