The answer is yes, if an individual's earnings are more than Rs. 20,000, they are required to pay professional tax. In Tamil Nadu, those who are salaried or self-employed are eligible for the payment of professional tax. It is essential to know this as an HR intern because, in the future, you will have to deal with staff and contractors too.
Your HR Manager can explain in detail the rest because there are more aspects that exist which are required for a business establishment, such as exemptions, etc.