how can we calculate the WHT tax on the total invoice amount??

Hello, I have a scenario where there are two taxes: Transaction tax and withholding tax for the same invoice.

When calculating the transaction tax, the amount in the line is different than the total invoice amount.

How can I add the WHT tax to be calculated based on the total amount of the invoice "2000" not on "1818"?

Is this option available for the same invoice or I have to split the invoice into two different invoices (one for the transaction and the other for WHT)?

split the invoices into two different invoices??