In Illinois they have to offer you what you were making in terms of money, not benefits.
So if you made $20,000 salary but worked 10 years and always got an extra $10,000 in bonuses, those bonuses wouldn’t factor into it.
Nor do things like heath insurance, time off, etc.
The states use a standard cost of living indicator which is unique to each state office. So you’d have to find out.
You also have to remember there are no hard and fast rules. If you were making $10.00/hr and you get offered $9.95/hr you’d be hard pressed to convince unemployment NOT to throw you off.
On the other hand in my example above with the commissions or bonuses, it doesn’t mean you can’t appeal. For example if you turned down that job in my example, you might get thrown off, but you can go to an appeal.
If you could make a convincing case to the arbitrator you may get back on.
When I worked in H/R my company fought every last unemployment claim, regardless, and the thing that amazed me was how inconsistant the ruling went.
Like two people get fired for being late constantly. One arbitrator would say, “tough luck-denied,” while the other arbitrator would say “Well he did try and get to work, he made the effort, so we’ll give it to him.”