As per the CA act teh CA is not allowed to practice without holding a valid COP. If for any reason your case comes up with the institute then it wold endanger your membership.
So get a valid COP from the institute & then do consulting. For I-t it would not be any problem as thye wont go into the details if you are holding any COP or not.
sir if a ca dont want to take COP then income earned by filing return of income or finalising accounts of Company should be shown under which head of income.