Illinois Business Tax Extension Filing Instructions
881 views | Last modified 3/20/2023 2:47:21 AM EST | Added by ExpressExtension Team

Businesses operating in Illinois (C-Corporation, S-Corporation, Partnership, Fiduciary and Exempt Organization) are granted an automatic six-month (seven-month for S-corporations) extension to file Illinois business tax returns. 

However, this extension does not grant you an extension of time to pay any tax you owe. If you expect the tax to be due, you must pay any tentative tax due, by the original due date of the return, in order to avoid interest and penalty on tax not paid by that date. 

Extension Form to use    

There is no state-specific form to request an IL tax extension, as the state of Illinois automatically provides the extension for up to 6 months for businesses to file an income tax return with the state.

Due date to file Illinois tax Extension

• Corporations - April 15, or same as IRS. Tax years ending with June 30, it is the 15th day of the 3rd month following the close of the tax year (September 15)
• S-Corporations - March 15, or same as IRS
• Partnerships - March 15, or same as IRS
• Fiduciary & Estate - April 15, or same as IRS

Illinois tax extension Filing Method (Paper/Electronic)

State of Illinois supports only the electronic filing method.

How to pay the state tax due?    

You can choose to pay your balance due along with your return by using any one of the following options:

• Pay by Online- Make Electronic Payments at any time.
• ACH Credit 
• Credit Card
• Check or money order(follow the payment instructions on the form or voucher associated with your filing)

1. Use Form IL-1120-V, payment voucher if you’re a C-corporation.
2. Use Form IL-1120-ST-V, Payment Voucher if you’re an S-Corporation
3. Use Form IL-1065-V, Payment Voucher if you’re a Partnership
4. Use Form IL-1041-V,  Payment Voucher if you’re a fiduciary

Note: You are NOT required to complete a payment voucher if you do not owe tax, or you make payment electronically.

Does ExpressExtension support this State filing?    

Illinois business extensions are automatic, which means there is no application to submit. If you have a valid Federal tax extension you will automatically be granted an extension for Illinois. 

However, you are still required to pay your Illinois tax by the original deadline to avoid penalties.

Any Special Requirements?

A tax extension does not give you more time to pay your state tax balance. If you owe any tentative tax, and you pay with a paper check or money order, file Form IL-505-B along with your payment voucher or electronically using the Illinois WebPay system on or before the original due date of your annual return, or as soon as you realize you owe tentative tax.

For more information regarding Illinois business state tax extension, click here.