Formost to clear you that BONUS is not paid every month.
It's paid once in a calendra year and it is included in the gross amount and professional tax is deducted.
Hope your calculating CTC amount every month. (As shown in above example).
Please Just don't get your self confussed.
Gross amount = All the allowance + OT Amount should be included.
You get good package software in the market where it is programed and done automatically (Payroll Package) . - Have to link your state Professional Tax slab to it.
From United Kingdom, London