In Receiver Matching, if the invoice was created in the initial state, the system always uses the withholding tax data calculated by GTM on the purchase order, and overwrites any withholding tax values you enter in the Withholding Tax tab of Supplier Invoice Initial Create.

If the invoice is not initial, the system uses the withholding tax entered, either manually or automatically by GTM, in the Withholding Tax tab of Supplier Invoice Create.