The business income tax e-File program is a 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 are allowed to be filed through MeF. Returns and payments can be transmitted together or separately. The Illinois MeF program will accept and process the three most recent years of business income tax returns on a rolling calendar basis.
BTR-36, Implementation Guide for Business Income Tax Federal/State Electronic Filing Program, for a list of returns and tax years that may be filed through MeF, program requirements, and more information.