Legal Question in Tax Law in Illinois

I think what you're really asking is whether some statute of limitations precludes Illinois from collecting. The answer is maybe. It depends on the kind of tax, how and when it was assessed and whether any intervening factor may extend out the time they have to collect. My advice, call them up and ask them why they believe the debt is collectible in 2015. Upon receiving a response, you can then look into any defenses you may have.