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Connect with a U.S.-based CPA or Enrolled Agent to prepare and file your Illinois business return. Upfront pricing, secure document upload, no surprises.
Connect with a TaxPro →Illinois LLCs and partnerships subject to the Personal Property Replacement Tax (PPRT) file with the Illinois Department of Revenue. Illinois grants an automatic 6-month extension to any LLC or partnership that holds an approved federal IRS Form 7004–no separate Illinois extension form is required.
Once your federal Form 7004 is approved by the IRS, your Illinois LLC or partnership return is automatically extended to September 15, 2026. Submit any Illinois PPRT owed using IL-1065-V | Payment Voucher for Partnership Replacement Tax by March 16, 2026, or pay electronically through MyTax Illinois. Mail payments to: Illinois Department of Revenue, P.O. Box 19053, Springfield, IL 62794-9053.
LLC / Partnership returns carry unique complexities – a licensed CPA or Enrolled Agent can navigate the details and ensure your Illinois return is filed accurately and on time.
Illinois requires online payment for tax amounts of $750 or more. Submit electronically via the Illinois Online Tax Extension Payment portal. For amounts under $750, complete IL-1065-V | Payment Voucher for Partnership Replacement Tax and mail with your payment.
Submit electronically through the Illinois Online Tax Extension Payment system. Required for all payments $750 and above.
Download IL-1065-V | Payment Voucher for Partnership Replacement Tax and mail with your check or money order. Include your EIN and tax year on the check.
| Penalty Type | Amount |
|---|---|
| Failure to File | Late filing: Lesser of $250 or 2% of tax liability. Nonfiling: Greater of $250 or 2% of tax liability up to $5,000 if return not filed within 30 days of nonfiling notice. |
| Failure to Pay | Before audit: 2% for payments 1 to 30 days late; 10% for payments 31 or more days late. After audit: 15% within 30 days of assessment; 20% after that period. |
| State Abbreviation | IL |
| Entity Type | LLC / Partnership |
| Extension Status | Automatic with approved IRS Form 7004 |
| Original Filing Deadline | March 16, 2026 |
| Extended Filing Deadline | September 15, 2026 |
| Payment Due | March 16, 2026 (100% of tax owed) |
| Payment Form | IL-1065-V | Payment Voucher for Partnership Replacement Tax |
| Online Payment | Illinois Online Tax Extension Payment |
| State Agency | Illinois Department of Revenue |
| Failure to File Penalty | Late filing: Lesser of $250 or 2% of tax liability. Nonfiling: Greater of $250 or 2% of tax liability up to $5,000 if return not filed within 30 days of nonfiling notice. |
| Failure to Pay Penalty | Before audit: 2% for payments 1 to 30 days late; 10% for payments 31 or more days late. After audit: 15% within 30 days of assessment; 20% after that period. |
Illinois S corporations–which are subject to the state’s replacement tax–file with the Illinois Department of Revenue. Illinois ties its business extension program to the federal process: an approved IRS Form 7004 automatically extends the Illinois S corporation deadline by 6 months to September 15, 2026, with no separate state filing required.
Secure an approved federal extension via IRS Form 7004 before March 16, 2026 and Illinois automatically honors it–no additional state form is required. Remit any Illinois S corporation tax using IL-1120-V | Payment Voucher for Corporation Income and Replacement Tax by March 16, or pay through MyTax Illinois. Mail payments to: Illinois Department of Revenue, P.O. Box 19038, Springfield, IL 62794-9038. File the completed return by September 15, 2026.
S Corporation returns carry unique complexities – a licensed CPA or Enrolled Agent can navigate the details and ensure your Illinois return is filed accurately and on time.
Illinois requires online payment for tax amounts of $750 or more. Submit electronically via the Illinois Online Tax Extension Payment portal. For amounts under $750, complete IL-1065-V | Payment Voucher for Partnership Replacement Tax and mail with your payment.
Submit electronically through the Illinois Online Tax Extension Payment system. Required for all payments $750 and above.
Download IL-1065-V | Payment Voucher for Partnership Replacement Tax and mail with your check or money order. Include your EIN and tax year on the check.
| Penalty Type | Amount |
|---|---|
| Failure to File | Late filing: Lesser of $250 or 2% of tax liability. Nonfiling: Greater of $250 or 2% of tax liability up to $5,000 if return not filed within 30 days of nonfiling notice. |
| Failure to Pay | Before audit: 2% for payments 1 to 30 days late; 10% for payments 31 or more days late. After audit: 15% within 30 days of assessment; 20% after that period. |
| State Abbreviation | IL |
| Entity Type | S Corporation |
| Extension Status | Automatic with approved IRS Form 7004 |
| Original Filing Deadline | March 16, 2026 |
| Extended Filing Deadline | September 15, 2026 |
| Payment Due | March 16, 2026 (100% of tax owed) |
| Payment Form | IL-1065-V | Payment Voucher for Partnership Replacement Tax |
| Online Payment | Illinois Online Tax Extension Payment |
| State Agency | Illinois Department of Revenue |
| Failure to File Penalty | Late filing: Lesser of $250 or 2% of tax liability. Nonfiling: Greater of $250 or 2% of tax liability up to $5,000 if return not filed within 30 days of nonfiling notice. |
| Failure to Pay Penalty | Before audit: 2% for payments 1 to 30 days late; 10% for payments 31 or more days late. After audit: 15% within 30 days of assessment; 20% after that period. |
Illinois C corporations pay corporate income and replacement taxes to the Illinois Department of Revenue. An approved federal IRS Form 7004 extends the Illinois C corporation filing deadline by 6 months–from April 15 to November 15, 2026–without any separate state extension application.
File IRS Form 7004 with the IRS before April 15, 2026 and Illinois automatically honors the 6-month extension. Pay any Illinois corporate tax using IL-1120-V | Payment Voucher for Corporation Income and Replacement Tax by April 15, or pay electronically through MyTax Illinois. Mail payments to Illinois Department of Revenue, P.O. Box 19038, Springfield, IL 62794-9038. Your completed Illinois C corporation return is due November 15, 2026.
C Corporation returns carry unique complexities – a licensed CPA or Enrolled Agent can navigate the details and ensure your Illinois return is filed accurately and on time.
Illinois requires online payment for tax amounts of $750 or more. Submit electronically via the Illinois Online Tax Extension Payment portal. For amounts under $750, complete IL-1065-V | Payment Voucher for Partnership Replacement Tax and mail with your payment.
Submit electronically through the Illinois Online Tax Extension Payment system. Required for all payments $750 and above.
Download IL-1065-V | Payment Voucher for Partnership Replacement Tax and mail with your check or money order. Include your EIN and tax year on the check.
| Penalty Type | Amount |
|---|---|
| Failure to File | Late filing: Lesser of $250 or 2% of tax liability. Nonfiling: Greater of $250 or 2% of tax liability up to $5,000 if return not filed within 30 days of nonfiling notice. |
| Failure to Pay | Before audit: 2% for payments 1 to 30 days late; 10% for payments 31 or more days late. After audit: 15% within 30 days of assessment; 20% after that period. |
| State Abbreviation | IL |
| Entity Type | C Corporation |
| Extension Status | Automatic with approved IRS Form 7004 |
| Original Filing Deadline | April 15, 2026 |
| Extended Filing Deadline | November 15, 2026 |
| Payment Due | April 15, 2026 (100% of tax owed) |
| Payment Form | IL-1065-V | Payment Voucher for Partnership Replacement Tax |
| Online Payment | Illinois Online Tax Extension Payment |
| State Agency | Illinois Department of Revenue |
| Failure to File Penalty | Late filing: Lesser of $250 or 2% of tax liability. Nonfiling: Greater of $250 or 2% of tax liability up to $5,000 if return not filed within 30 days of nonfiling notice. |
| Failure to Pay Penalty | Before audit: 2% for payments 1 to 30 days late; 10% for payments 31 or more days late. After audit: 15% within 30 days of assessment; 20% after that period. |
Illinois estates and trusts with fiduciary income tax obligations report to the Illinois Department of Revenue. Illinois grants fiduciary filers the same federal-tied extension benefit–an approved IRS Form 8868 automatically extends the Illinois fiduciary filing deadline from April 15 to October 15, 2026 without any state form required.
File IRS Form 8868 with the IRS before April 15, 2026 and Illinois automatically extends the fiduciary return to October 15, 2026–no separate state extension form is needed. Submit any fiduciary tax payment using IL-1041-V | Payment Voucher for Fiduciary Income and Replacement Tax by April 15, or pay through MyTax Illinois. Mail payments to: Illinois Department of Revenue, P.O. Box 19053, Springfield, IL 62794-9053.
Fiduciary / Estate / Trust returns carry unique complexities – a licensed CPA or Enrolled Agent can navigate the details and ensure your Illinois return is filed accurately and on time.
Illinois requires online payment for tax amounts of $750 or more. Submit electronically via the Illinois Online Tax Extension Payment portal. For amounts under $750, complete IL-1065-V | Payment Voucher for Partnership Replacement Tax and mail with your payment.
Submit electronically through the Illinois Online Tax Extension Payment system. Required for all payments $750 and above.
Download IL-1065-V | Payment Voucher for Partnership Replacement Tax and mail with your check or money order. Include your EIN and tax year on the check.
| Penalty Type | Amount |
|---|---|
| Failure to File | Late filing: Lesser of $250 or 2% of tax liability. Nonfiling: Greater of $250 or 2% of tax liability up to $5,000 if return not filed within 30 days of nonfiling notice. |
| Failure to Pay | Before audit: 2% for payments 1 to 30 days late; 10% for payments 31 or more days late. After audit: 15% within 30 days of assessment; 20% after that period. |
| State Abbreviation | IL |
| Entity Type | Fiduciary / Estate / Trust |
| Extension Status | Automatic with approved IRS Form 7004 |
| Original Filing Deadline | April 15, 2026 |
| Extended Filing Deadline | October 15, 2026 |
| Payment Due | April 15, 2026 (100% of tax owed) |
| Payment Form | IL-1065-V | Payment Voucher for Partnership Replacement Tax |
| Online Payment | Illinois Online Tax Extension Payment |
| State Agency | Illinois Department of Revenue |
| Failure to File Penalty | Late filing: Lesser of $250 or 2% of tax liability. Nonfiling: Greater of $250 or 2% of tax liability up to $5,000 if return not filed within 30 days of nonfiling notice. |
| Failure to Pay Penalty | Before audit: 2% for payments 1 to 30 days late; 10% for payments 31 or more days late. After audit: 15% within 30 days of assessment; 20% after that period. |
Work with a U.S.-based CPA or Enrolled Agent who knows Illinois business taxes – secure upload, upfront pricing, and on-time filing.
Connect with a TaxPro →