Income tax return

Hi, Everybody,

I am running dance academy since 2004 which I have never registered at any place. Now, I would like to file Income Tax return under "PGBP" since 2004 for "NIL". Since I need to prove that I am self employed through my academy from 2004 to Canadian embassy.

How much old returns we can file? (how many years? 'NIL')

Please Reply soon.

Regards,

Nirmit