Illinois
State Business Tax Extension

What Form does the state of Illinois require to apply for
an extension?

There is no state-specific form to request an 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.

How do I pay my balance due to the state of Illinois with
my extension?

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

• Electronic Payments through https://mytax.illinois.gov/
• ACH Credit through https://mytax.illinois.gov/
• Credit Card
• Check or money order
  • Use Payment Voucher Form
    IL-1120-V - If your business is
    a Corporation
  • Use Payment Voucher Form
    IL-1120-ST-V - If your business is a Small
    Business Corporation
  • Use Payment Voucher Form
    IL-1065-V - If your business is
    a Partnership

When is the deadline to file a business tax return with the State
of Illinois?

• Businesses in Illinois (operating as C-Corporations) must file their
  Form IL-1120 by the 15th day of the 4th month following the end of their accounting period.
• Businesses in Illinois (operating as S-Corporations) must file their
  Form IL-1120-ST by the 15th day of the 3rd month following the end of their accounting period.
• Businesses in Illinois (operating as a partnerships) must file their
  Form IL-1065 by the 15th day of the 4th month following the end of their accounting period.
• Businesses in Illinois (operating as Fiduciaries) must file their
  Form IL-1041 by the 15th day of the 4th month following the end of their accounting period.
• Businesses in Illinois
  (operating an Exempt Organization)
  • If 501(c) trusts must file their Form IL-990T by the 15th day of the 5th month following the end of their accounting period.
  • If 401(a) trusts must file their Form IL-990T by the 15th day of the 4th month following the end of their accounting period.