WHT , fixed amount

Hi Guys

As per our federal tax board in our region , we have to deduct fixed amount  of with holding tax on range basis. For example

if

amount  range   0   to 200,000             WHT must be deducted 12,000 ( fixed figure)

amount  range   200,001   to 400,000             WHT must be deducted 24,000 ( fixed figure)

Kindly tell me the possible solution.

Regards

Q.A