How to set the value added tax on the invoice?

Can I remove withholding tax on desktop edition and add value added tax 20%?

You don’t remove withholding tax on any edition, you just don’t tick the box if it’s not required.

To add VAT, got to Settings - Tax Codes and select your countries rate from the drop down. If its not listed then use the Custom feature to add your Tax Code

Tnx. Serbian language version does not have the option tax codes. I switched to English, is now working. Thank you so much for your prompt response. program is an excellent.