Itr not filed for 6 years

Dear Members

One of my client filled his IT return upto AY 2004-05 (tax paid in AY 2004-05 was Rs.17000) and failed to file his return from AY 2005-06 till now .

My client's profession is Pastor(Conducting prayers) and during the last 6 years he undergo a by-pass surgery and his income was below the taxable limit during AY 2005-06 to 2010-11.

My doubt is whether we can file the return for AY 2011-12& 2012-13 only or for the last 7 years.

And what is the procedure for filing the return of income from 2005-06 to 2010-11.

Thanks in advance

Regards

CA. Santhos Kumar.S