I formed an LLC in 2009 and the only activity was $51.16 in interest income. The LLC received a 1099-INT. Do I need to file a federal return or state return (in IL)? Thx.

Is the LLC a sole proprietorship? If so, then report the interest income on your PERSONAL tax return for both the federal return and the Illinois return.

If the LLC is a partnership, then Form 1065 and the Illinois equivalent must be filed.