Handle partial captures and overcaptures for variable-amount transactions

Steps

1. Create an authorization for the maximum expected amount (e.g., a product estimate plus a buffer for overages), keeping the capture separate from the authorization.
2. When the final amount is known, submit a capture request for the actual amount; if less than the authorized amount, the remaining hold is released to the cardholder.
3. For overcaptures (final amount exceeds the authorized amount), check whether your gateway and acquirer support overcapture and up to what percentage above the original authorization.
4. If overcapture is not supported, submit an incremental authorization for the additional amount before capturing the combined total.
5. Reconcile captured amounts against your order management system; flag any mismatch between the captured amount and the order total for manual review.
6. Void any unused authorizations promptly to release cardholder funds and reduce your authorization-to-capture ratio, which affects interchange rates.