The Illinois Department of Revenue (IDOR) , in conjunction with the Internal Revenue Service (IRS), accepts electronically filed business income tax and individual income tax returns as part of the IRS Modernized e-File (MeF) Program. MeF is a web-based system that allows electronic filing of tax returns through the Internet. MeF uses the widely accepted Extensible Markup Language (XML) format.
Linked (combined) federal/state filings and unlinked (state-only or state standalone) returns, along with payments (estimated payment(s), extension and tax payments) are allowed to be filed through MeF. The Illinois MeF program will accept and process three years of business income tax returns on a rolling calendar basis. Presently, the Illinois MeF program for individual income tax will only accept and process the current year IL-1040.
All entities wishing to participate must register with the IRS and be accepted in order to participate in MeF. Software developers are required to register and test their product with IDOR. Software developers for business income tax MeF must register with IDOR using Form IL-8633-B, Business Electronic Filing Enrollment. Software developers for individual income tax MeF must register with IDOR using Form IL-8633-I, Application to File Illinois Individual Income Tax Returns Electronically for Software Developers.
For additional information on business income tax MeF see BTR-36, Implementation Guide for Business Income Tax Federal/State Electronic Filing Program and for information on what forms/schedules are currently accepted see IL-1120 MeF "Live" List.