Sorry to differ, the question was not whether the amount of bonus should be taken as income received for the purpose of calculation of professional tax but whether the bonus shall be calculated on the basis of salary declared for professional tax calculation or not. I also differ that bonus is not considered for the calculation of income for payment of professional tax because professional tax is a tax on profession, and not a tax on 'salary'. Therefore, whatever is earned by a professional, businessman, employee, trader, freelancer, etc., should attract professional tax.
In the case of an employed person, the income earned shall include a bonus, and in the half-year (normally all the states have payment of professional tax on a half-yearly basis, and I believe that the same is the system in West Bengal also) bonus is received, for that half-year, professional tax should be calculated based on salary including bonus. Simply put, a bonus is an income in the hands of a salaried person for the purpose of income tax, and in the same way, it is an income for the computation of professional tax payable.