Working as consultant

It boils down to the terms of your engagement with the organization. In case, you join them as a consultant and they deduct only TDS for professional services then there is no restriction on your part to hold a Certificate of Practice unless and until the terms of engagement bar you from holding a COP.

On the contrary, if you are a full time consultant on the rolls of the organization, and you are paid salary,then employer-employee relationship kicks in and you can not hold full time certificate of practice. Beware of professional ethics on this front, some of them tacitly and deceitfully violate this provision.