How do I find out if my new husband owes taxes from a previous year?

I got married last summer and my new husband told me I have to file separate I know he will owe taxes for 2009 but how do I find out if he owes for any previous year? I think I might file his taxes for him for 09 because he doesn't seem to have any plans for doing them. What should I do? I don't want to be penalized because he didn't do them.