My green card expires in less than a year however I won't be renewing it b/c it will prob. get denied due to legal issues.

I have been working and paying taxes for almost 10 years now and after it expires I will continue to work and file income taxes. What are the consequences of not renewing my green card? Is one considered an Illegal immigrant the day their permanent residency expires? Am I working illegally? Is there a time frame one might expect before ICE deports me?