unable to change recoverable or non recoverable tax amount in ap invoice worhbench.

Hello,

we have done setup in such a way that all the tax amount will go to non recoverable tax, but in some cases it will be part of recoverable tax., in this case we want to change amount in ap invoice worhbench,

my doubt is:

is it possible to change amount , if yes, than what setup is required and which level.

Thanhs