Withholding tax for customer is not calculated as it is done when using payment journals, when trying to settle invoices with prepayments using customer open transactions.
Actually this is how the withholding tax feature was designed, the withholding tax is calculated only in the payment journal lines.
A workaround for that is, in the payment journal lines > Functions > Settlement, you may select the invoice (which will calculate the withholding tax) and also select the prepayment line, so these vouchers will be matched against each other and you'll have only the difference of this result, then you may proceed with the payment posting.
The withholding tax may be calculated as a percentage of the payment amount in a month. The withholding tax is calculated over all invoices to be paid to vendors or by customers in the same calendar month or invoice according to the withholding tax code configuration.
In Brazil, the withholding tax is applied over purchase and sale of services during the payment.
Article ID: 2419650 - Last Review: Aug 5, 2011 - Revision: 1