INSTRUCTIONS: ILLINOIS INDIVIDUAL INCOME TAX RETURN (Form IL-1040)

Illinois residents, part-year residents and non-residents file their state income tax due using a form IL-1040. This document can be found on the website of the Illinois Department of Revenue.

Illinois Individual Income Tax Return IL-1040 Step 1: If you are not filing on a calendar year basis, give the ending month and year of your fiscal year.

Illinois Individual Income Tax Return IL-1040 Step 2: Enter your Social Security number on line A, as well as that of your spouse if filing jointly.

Illinois Individual Income Tax Return IL-1040 Step 3: In section B, give your name and address. Enter your spouse's first name and, if different and filing jointly, last name.

Illinois Individual Income Tax Return IL-1040 Step 4: On line C, indicate your filing status with a check mark.

Illinois Individual Income Tax Return IL-1040 Step 5: On line D, check the box if you are a member of a same sex civil union.

Illinois Individual Income Tax Return IL-1040 Step 6: On lines 1 through 4, document your income as instructed.

Illinois Individual Income Tax Return IL-1040 Step 7: On lines 5 through 10, calculate and document your base income as directed.

Illinois Individual Income Tax Return IL-1040 Step 8: On lines 10a through 10d, note all applicable exemptions being claimed.

Illinois Individual Income Tax Return IL-1040 Step 9: Residents calculate their net income on line 11, while non-residents and part year residents do so on line 12.

Illinois Individual Income Tax Return IL-1040 Step 10: Residents calculate their tax on line 13, while non-residents and part year residents do so on lines 14 and 15.

Illinois Individual Income Tax Return IL-1040 Step 11: Calculate your tax after the application of nonrefundable credits on lines 16 through 20. Transfer the value on line 20 to line 21 on the second page.

Illinois Individual Income Tax Return IL-1040 Step 12: Calculate other taxes on lines 22 through 24 as applicable.

Illinois Individual Income Tax Return IL-1040 Step 13: Apply payments already made and refundable credits on lines 25 through 29. Overpayments should be entered on line 30, while underpayments should be entered on line 31.

Illinois Individual Income Tax Return IL-1040 Step 14: If you have underpaid, complete lines 32 through 34. If you have overpaid or are due a refund, complete lines 35 through 39.