Filing Requirements
Who must file an Illinois tax return?
An Illinois resident taxpayer, must file Form IL-1040, Individual Income Tax Return, if- you filed a federal income tax return electronically or by paper; or
- you were not required to file a federal income tax return, but your Illinois base income is greater than your Illinois exemption allowance.
An Illinois resident taxpayer who worked in Iowa, Kentucky, Michigan, or Wisconsin, must file Form IL-1040 and include as Illinois income any compensation you received from an employer in these states. Compensation paid to Illinois residents working in these states is taxed by Illinois. Based on reciprocal agreements between Illinois and these states, these states do not tax the compensation of Illinois residents.
If your employer in any of these states withheld that state’s tax from your compensation, you may claim a refund of that state’s tax withheld by filing the correct form with that state. You may not claim tax withheld by an employer in these states as a credit on your Illinois return.
A retired Illinois resident taxpayer who filed a federal return, you must file a Form IL-1040. However, certain types of retirement income (e.g., pension, Social Security, governmental deferred compensation) are not taxed by Illinois. For more information, see the instructions for Line 5 and Publication 120, Retirement Income.
A part-year resident taxpayer (i.e., you were a resident of Illinois for part but not all of the tax year), must file Form IL-1040 and Schedule NR, Nonresident and Part-Year Resident Computation of Illinois Tax, if
- you earned income from any source while you were a resident,
- you earned income from Illinois sources while you were not a resident, or
- you want a refund of any Illinois Income Tax withheld.
A nonresident taxpayer (i.e., you were not an Illinois resident at any time during the tax year), must file Form IL-1040 and Schedule NR if
- you earned enough taxable income from Illinois sources to have a tax liability (i.e., your Illinois base income from Schedule NR is greater than your Illinois exemption allowance on Schedule NR), or
- you want a refund of any Illinois Income Tax withheld in error. You must attach a letter of explanation from your employer.
For more information, refer to Schedule NR, Nonresident and Part-Year Resident Computation of Illinois Tax, and that schedule’s instructions.
An Iowa, Kentucky, Michigan, or Wisconsin resident who worked in Illinois, must file Form IL-1040 and Schedule NR if- you received income in Illinois from sources other than wages, salaries, tips, and commissions (you must pay tax on this income regardless of residency);or
- you want a refund of any Illinois Income Tax withheld.
If you received compensation from Illinois employers, you are not required to pay Illinois Income Tax on this income. This is based on reciprocal agreements between Illinois and these states and applies only to compensation you received from wages, salaries, tips, and commissions. The reciprocal agreements do not apply to any other income you might have received, such as Illinois lottery winnings.
An Illinois resident who was claimed as a dependent on your parents’ or another person’s return, might not be exempt from tax. You must file Form IL-1040 if- your Illinois base income is greater than $2,000, or
- you want a refund of Illinois Income Tax withheld from your pay.
Note: If your parent claimed your interest and dividend income through U.S. Form 8814, do not count that income in determining if you must file your own Form IL-1040.
The surviving spouse or representative of a deceased taxpayer who was required to file in Illinois, you must file any return required of that taxpayer. Please refer to the special instructions on how to file for a deceased taxpayer.
A student, is not exempt from tax nor are there special residency provisions for you. However, income, such as certain scholarships or fellowships, that is not taxable under federal income tax law, is also not taxed by Illinois.
A nonresident alien taxpayer, is not exempt from tax. If your income is taxed under federal income tax law, it is taxed by Illinois. You must attach a completed copy of your U.S. 1040NR or U.S. 1040NR-EZ.
Even if you are not required to file Form IL-1040, you must file to get a refund of any Illinois Income Tax withheld from your pay or any estimated tax payments you made.
