How to Get Illinois Tax Forms: Official Sources

Obtaining Illinois Tax Forms (IL-1040, IL-1120, etc.)

The Illinois Department of Revenue (IDOR) provides all state tax forms free of charge.

1. Online (Fastest & Most Current)

• IDOR Forms & Publications: tax.illinois.gov/forms
• Search by form number (IL-1040, IL-1120, IL-941, ST-1, etc.) or category.
• PDF fillable + instructions. Always use current year.

2. By Mail

• Call 1-800-356-6302 (Forms Order Line).
• Write: Illinois Department of Revenue, Forms Distribution, PO Box 19001, Springfield, IL 62794-9001.
• Specify form numbers & quantities.

3. In Person

• IDOR Offices: Springfield (Willard Bldg), Chicago (Thompson Center), Des Plaines, Fairview Heights, Marion, Rockford. Check tax.illinois.gov/contact for hours.
• Libraries / Post Offices: Many stock basic forms (IL-1040, schedules) Jan–Apr.

4. Tax Software (Auto-Populated)

• TurboTax, H&R Block, TaxAct, FreeTaxUSA, Cash App Taxes: Include IL forms; e-file state + federal.
• IL Free File: tax.illinois.gov/individuals/efile.html — free federal+state for AGI ≤ $79k.

5. Tax Professionals

• CPAs, EAs, tax prep firms — they have current forms & software.

Key 2023 Forms (Filed 2024)

• IL-1040: Individual Income Tax Return
• IL-1040-ES: Estimated Tax Vouchers (Individuals)
• IL-1120: Corporation Income Tax Return
• IL-1120-ES: Estimated Tax Vouchers (Corporations)
• IL-941: Employer's Quarterly Withholding Return
• ST-1: Sales & Use Tax Return
• IL-505-I: Automatic Extension (Individuals)

Filing Deadlines

• Individual: April 15 (auto 6-mo extension to Oct 15 with IL-505-I).
• Corporate: 15th day of 4th month after tax year end.
• E-filing mandated for most preparers & corporations.