The offense is punishable as a class A misdemeanor offense. The maximum sentence under the law is $2,500 and/or up to one year in the county jail. A non-DUI related second violation for driving during a suspension will require at least 300 hours of community service. It may be possible to secure court supervision due to a quirk in how the statute is written but this is highly unlikely. If the you are not granted the option of community service, the only option otherwise available is some period of jail.
If the suspension related from a DUI or an incident involving serious injury/death, a second offense carries the potential for felony enhancement which carries not only mandatory prison time if convicted but also a felony conviction on your record.
Beyond the criminal penalty, driving on a suspended license can seriously damage your driving privileges. Under Illinois law, “the period of suspension shall be extended for an additional like period of time as the original suspension if the suspension is in effect at the time the conviction is recorded to the driving record”. This means that a suspension of 3 months, even if already terminated, can result in 3 further months of suspension. In the event that you are already suspended, the Secretary of State “shall suspend for a like period of time as the original suspension if the suspension has terminated at the time the conviction is recorded to the driving record”. This means that the suspension time will be increased by the amount you were previously suspended turning a 3 month suspension into a 6 month suspension.
While this is a harsh outcome, it is possible to be convicted of driving while license suspended and not have this automatic suspension rule trigger depending on why your license was suspended at the time. Whether your specific underlying suspension will trigger this suspension extension penalty is a matter that would be best addressed by speaking to a lawyer. Lastly, if you can receive court supervision, it will prevent any negative outcome from occurring at the secretary of state as they do not consider supervision as a result which triggers a suspension.
The best way to avoid the negative effects of jail, a criminal record, and future license suspensions is to speak to an attorney and have them analyze your exact situation.