Non-filing of service tax nil return

Friends,

One of my friend - a sole proprietor, had registered under service tax 4 years ago, but has not filed any returns till date as he has not done any business. What are the consequences of non-filing of NIL returns? Will there be any penalty? If yes, is there a way to avoid it? If he wants to surrender the registration, will the non-filing be a issue? Please suggest a cost-effective and simple way out.

Thanks & Regards,

Maheswari