CA
                
                   397 Points
                   Joined February 2011
                
               
			  
			  
             
            
             This in principally is a is a violation of FEMA Deposit Regulations. You should advise your client to immediately re-designate accounts to NRO. Also, update NRI status in all investments in India.  
Penalty as per FEMA is three times of amount if it is quantifiable else a flat penalty of INR 2 lacs. 
Practically speaking, there are thousands of NRIs who still hold resident accounts partly due to ignorance and partly due to lack of enforcement of legal provisions. I have not come across a case of penalty levied for this breach. 
Ask client if he has carried out any big transaciton in contravention of FEMA - like purchasing agricultural property, or trading in shares through resident demat (and not PIS) account - in such case, it is advisable to write to RBI admitting the violation - if RBI feels it is a fit case for compounding, you can pay a small fee and regularise the transaction. 
Kindly refer to this post for more clarity on this subject: https://www.abhinavgulechha.com/fema-contravention/
Thanks!