You must file Form IL-1041, Illinois Fiduciary Income and Replacement Tax Return, if you are a fiduciary of a trust or an estate and the trust or estate
Grantor Trusts do not file Form IL-1041. Instead, the income earned from the trust is shown on the grantor's Form IL-1040, Individual Income Tax Return.
If the trust is a charitable organization exempt from federal income tax by reason of the Internal Revenue Code (IRC), Section 501(a), it is not required to file Form IL-1041. However, unrelated business taxable income, as determined under IRC, Section 512 is subject to tax, without any deduction for the Illinois income tax, and must be reported on Form IL-990-T, Illinois Exempt Organization Income and Replacement Tax Return, instead of Form IL-1041. For more information, see Form IL-990-T Instructions.