Deduct withholding tax question

When creating a new sales invoice I have to choose Deduct withholding tax which is 3% on the subtotal in my country, not on the total amount of the invoice.
On Manager I have two options: 1 is Amount in which I insert the amount of 3% manually
2 is Rate which automatically inserts the amount after putting the percentage .
Is it possible for me to choose the 2 option and change the calculation to the subtotal amount?

Sub-total € 3.768,62
ΦΠΑ 24% € 904,47
Total € 4.673,09
Withholding tax € 113,06 >=subtotal*3%
Balance due € 4.560,03

Thank you.

Your question is not clear. If you are asking whether you can calculate the withholding on the subtotal rather than the total including any tax, the answer is no.

If your jurisdiction allows withholding to be computed on anything besides the total, calculate it manually and enter the amount rather than the percentage. In most jurisdictions, the percentage is applied to everything, including taxes.

Good Morning.
@Tut your answer is clear but not what I expected.