It is calculated based on the total six-monthly gross salary + whatever additional incomes like bonus, incentives, increment arrears, etc., and the same is described under different salary slabs for different cities.
Then the PT amount worked out as per the slab is divided by 6 and recovered from the salary every month for six months. (Two six-monthly calculations in a financial year)
The slabs are made like up to 21000, 30000, 45000, 60000, 75000, above 75000, etc.
Let us presume that everyone's monthly gross salary is above Rs. 12500/-
In that case, everyone's total six-monthly gross salary is above Rs. 75000/-. Once the professional tax for those above 75000/- (six-monthly gross income) is so and so amount, then what difference is it going to make if we add a bonus or incentive or special incentive, etc., and make it 1,75,000 or 17,50,000/- or whatever amount.
The PT amount is going to remain the same for this category of people.
Of course, for those who are drawing six-monthly gross salary between 21000 to 75000, the calculation will change as per the slabs due to the addition of a bonus or incentive or increment, etc.
I think hardly anyone is drawing less than 12500 per month, at least in metro cities.
Regards,
S. Kumarasubramanian