Withholding Tax for Section 197

Hello Friends,

I am trying to complete the configuration for Section 197 implementation,

As per requirement, Reaching the value of transaction for one of the Vendor it should reduce the tax percent.

For ex. Vendor A should reach the transaction of Rs. 100 Corers. then system should reduce the tax rate from 10% to 7%.

Can any one please help what is the point in the configuration to reduce the withholding tax calculation.

Thanks in advance,

Rajesh. K