Filing income tax of my previos year

Hi, I am an individual tax payer (ITR-1)

I am salaried, I work as accountant in a business firm from last 2 years. I do not get any form-16 issued from this busines firm.

This year I applied for PAN and have for my PAN number and I am planning to file my return for A.Y 2012-13.

I also want to file my return for last A.Y (2011-12) - Please let me know as per income tax rules do I have to pay any penalties for late filing of return ?

For both current year and last year, my income is not taxable (meaning its withing the tax slab limit) but  as Form-16 is not issued by my firm (employer) - I want to file my return for both this year and lats year.

Also provide income tax  site refernces for the same (if possible)

Thanks a lot.