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Illinois Department of Revenue
2023 Form IL-1040-X Instructions
General Information
Should I file Form IL-1040-X? You must file Form IL-1040-X, along with proper supporting
You should file Form IL-1040-X, Amended Individual Income Tax documentation, for both corrected and amended returns.
Return, if you need to change a previously filed Form IL-1040, Note: If your amended return is filed incorrectly and additional liability
Individual Income Tax Return, due to a change that affects items used is due, we must issue you a notice of deficiency within two years from
to figure your Illinois net income or credits. the date you filed Form IL-1040-X. If you fail to file an amended return
Your change can occur from a state change or a federal change, i.e., when required, we may issue you a notice of deficiency at any time.
an amendment of your federal income tax return, Note: If an amended return claiming a credit or refund is filed within
an adjustment made by the Internal Revenue Service (IRS), or six months of the expiration of the statute of limitations, the statute of
any other recomputation or redetermination. limitations will automatically be extended an additional six months for
You should file Form IL-1040-X only after you have filed a issuing an assessment of additional tax due.
processable Illinois Income Tax return. You must file a separate Form
IL-1040-X for each tax year you wish to change. Do not file another What if I have a net operating loss (NOL)
Form IL-1040 with “amended” figures to change your originally filed deduction or net Internal Revenue Service (IRS)
Form IL-1040.
section 1256 contracts loss?
Note: Do not file Form IL-1040-X if you are only changing your In general, Illinois allows you to take the same NOL carryback
name, address, or Social Security number. Instead, forward or carryforward deduction or net IRS section 1256 contracts loss
this information to the address provided under ‘‘What if I need carryback allowed on your federal income tax return. A carryback
assistance?’’ or update your information electronically on our account deduction is a “federal change” that reduces your federal adjusted
management program at mytax.illinois.gov. gross income (AGI) on Step 2, Line 1. For either an NOL or net IRS
section 1256 contract loss carryback, check the box marked “NOL” on
Which revision of Form IL-1040-X should I use? Step 1, Line F, and indicate the date the IRS accepted your carryback
To amend, use the Form IL-1040-X for the year you are amending. deduction. This will usually be the date on which the IRS issued your
If you are amending your Form IL-1040 for 2007 or earlier, you must refund check. You must file Form IL-1040-X within 2 years plus 120
use the 10/08 revision of Form IL-1040-X (for 2007 and earlier tax days after that date to be eligible to receive a refund.
years). Illinois does not allow you to deduct the same NOL twice. To prevent
a double deduction of your NOL when you have any NOL remaining
How long do I have to amend my return? to carry to a later year, your deduction for a tax year cannot be greater
The amount of time you have to amend your return depends on than the federal NOL available for deduction in that year minus the
whether your Form IL-1040-X is being filed due to a state change or a federal NOL available to carry to later years. This is the lesser of the
federal change. loss available in the year or the amount reported as “modified taxable
State change only – If your change decreases the tax due to Illinois income” on federal Form 1045, Application for Tentative Refund,
and you want a refund, you must file an amended return (claim for Schedule B, Line 9.
refund) within For an NOL carryback, attach a copy of your federal Form 1045
three years after the extended due date, Schedule B.
three years after the date your original return was filed, or If you are a resident in the year you are allowed a federal NOL
one year after the date your Illinois tax was paid, deduction, Illinois allows you to deduct the entire amount even if
whichever is latest. you were not a resident in the year the loss occurred. If you are a
Note: The refund allowed on a claim filed within three years after the nonresident or part-year resident in the year you are allowed the federal
original return was filed is limited to the total of all payments made NOL deduction, see the instructions for Step 3, Line 19, of Illinois Schedule
within three years and six months prior to the filing of the refund claim. NR, Nonresident and Part-Year Resident Computation of Illinois Tax.
If your change increases the tax you owe to Illinois, you should file a Example: In tax year 2023, Paul Taxpayer, a nonresident individual,
Form IL-1040-X and pay the tax, penalty, and interest as soon as you has $20,000 in federal net losses from Partnership A and $180,000
realize that it is owed. in net losses from Partnership B. He has $100,000 in income from
Federal change (including NOLs and net section 1256 contracts other sources, so his AGI for 2023 is a net operating loss of $100,000.
losses) – If your federal change decreases your Illinois tax, and you Federally, Paul Taxpayer carries the entire $100,000 loss back to
want a refund, you must file an amended return (claim for refund) 2021.
within two years plus 120 days of federal finalization. Ten percent of the $100,000 net operating loss deduction for 2021 is
Note: If your federal change resulted in an overpayment or if you attributable to Partnership A (Partnership A’s $20,000 loss in 2023 is
claimed a net operating loss (NOL) carryback, you should not file divided by the $200,000 in total losses incurred from partnerships in
this form until you receive a federal finalization notification from the 2023) and 90 percent of the net operating loss deduction is attributable
IRS stating that they have accepted your change either by paying a to Partnership B. See the Schedule NR Instructions for Step 3,
refund or by final assessment, agreement, or judgment. Line 19, to determine the amount of each partnership’s net operating
loss deduction amount that is allocated or apportioned to Illinois.
If your federal change increases your Illinois tax, you must file a
Form IL-1040-X and pay any additional tax within 120 days of the For a net IRS section 1256 contracts loss carryback, your deduction for
federal finalization date (the date you filed your federal Form 1040-X and a tax year cannot be greater than the loss amount on Line 1 of the US
paid the tax due), or you may be assessed a late-payment penalty. 6781 for the carryback year, and the allowable loss amount cannot be
greater than the gain listed on Line 1 of US 6781 for the carryback year.
Note: Any Form IL-1040-X filed prior to the automatic extension date For a net section 1256 contracts loss carryback, attach a copy of your
will be considered a “corrected” rather than an amended return and
federal Form 6781, Gains and Losses From Section 1256 Contracts and
any penalties and interest may be refigured.
Straddles for the carryback year.
In most cases, if you file an amended return after the extended due
date, any penalty for late payment of estimated tax will remain as
originally assessed.
IL-1040-X Instructions (R-12/23) Printed by authority of the state of Illinois, electronic only, one copy. Page 1 of 5
