How to have Automatic / Manual Sales Tax at the same time

Hello,

I've been defined Non-Recoverable Taxes and the requirement is :-

- To make the tax automatically calculated ONLY once I select the " Tax Classification Code" from Invoice Line

Other than that the system should not calculate the Tax at the invoice Validation action.

I've been tried to unchecked the  "Allow Tax Applicability" : @ >Defaults and Controls-->Configuration Owner Options

But this results to disable automatic tax calculation on this combination of configuration owner and event class which is not the requirements

Can anyone help me on this Guys, Thanks in advance