Fileing of itr without pay tax

Respected Seniors,

One of my client file itr online through a tax consultant without paying tax and also showing wrongly higher income in the month of June 2013 for the financial year 2012-13. Can I rectify it, and also his volume of actual income lesser than earlier return. If I now file the return after rectifying, what are the consequences after filing return. Please briefing me. Thanks