If you are a nonresident spouse living in Illinois because your service member is stationed here under military orders, and you share the same home state as the service member, Illinois does not tax the wages you earn in Illinois. You still pay tax on those wages to your home state if that state requires it.
There is nothing to apply for with Illinois. Give your Illinois employer the withholding paperwork claiming the exemption, and file your income tax return with your home state instead.
A copy of the service member's orders assigning them to Illinois, your military ID, and proof of your shared state of residence such as a driver license or voter registration.
