Where can i give the Tax Rate for exempt Tax Code-O0 in FTXP

Hi,

I have to give the tax rate 0% for Exempt tax code-O0 in FTXP transaction.Kindly advice me where can i put the 0% in FTXP.

In which area i have to give the 0% either MW1 area or NVV area? (This is for customers)

Thanks

Supriya