For Illinois purposes, you should report the taxable income you are reporting for federal purposes under IRC Sections 881 through 885. The rules vary for withholding income tax on employees who temporarily travel outside of their resident state for work.Business travel deductions are available when employees must travel away from their tax home or main place of work for business reasons. Commuting is not considered business mileage and is not deductible. You would fill out Form 2106 to take these expenses. Regards,. A sample filledin Business Expense Reimbursement Form is located in the appendix. No information is available for this page. Are employers required to withhold outofstate taxes? No one completing Illinois taxes for the first time can submit and pay online. These expenses are considered as income tax deductions and reported on form 1040.