Depending on your city, check the professional tax rate slab. In Mumbai, people earning a salary of more than ₹10,000 gross pay a professional tax of ₹2,500 annually (₹200 per month from March to January and ₹300 for February). Also, note that PT is not deducted on a pro-rata basis; it's a fixed amount. So, even if the person works for only 2-3 days of a month and gets a salary for that month, we are to deduct PT for that month. Therefore, it is immaterial about 15 days of work.
From your profile, I believe you are from Delhi and so is your firm. I have found an article that states that PT is not applicable in New Delhi. Check it at
http://What is Professional Tax and ...Rate in India?
Hope this helps you...