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IL-1120-X Instructions (R-12/23)
For instructions regarding completion of Steps 1 through 7, refer
to the Form IL-1120 Instructions and schedules for the year being
amended.
Specic instructions for most of the lines are provided on the
following pages. If a specic line is not referenced, follow the
instructions on the form.
Enter the tax year you are amending in the space provided at the top
of Form IL-1120-X.
Step 1: Identify your corporation
A — Type or print your legal business name. If you have a name
change from your original return, check the corresponding box.
B — Type or print your mailing address.
C — If you are ling an Illinois combined unitary return, check this
box and attach a complete and corrected Illinois Schedule UB. If you
are a foreign insurer, check the box and, if you are entitled to a tax
reduction, attach a completed Illinois Schedule INS, Tax for Foreign
Insurers. Combined unitary return lers with one or more foreign
insurer members, check both boxes and follow the instructions for
both boxes. If your unitary group is entitled to a tax reduction, attach
a completed Illinois Schedule UB/INS, Tax for a Unitary Business
Group with Foreign Insurer Members.
See the specic instructions for Step 8 in order to claim the
tax reduction calculated on Schedule INS or Schedule UB/INS.
D — Check the box if you are ling this form only to report an
increased net loss, you have no surcharges for Compassionate
Use of Medical Cannabis Program Act or sale of assets by gaming
licensee on your original or amended return, and no overpayment
will result. Complete Steps 2 and 3, Step 4, if applicable, and Step 5,
Lines 35 through 37. Sign the return in Step 9 and leave the rest of
the form blank.
E — If you completed federal Form 8886 or federal Schedule M-3,
Part II, Line 12, to report a tax shelter and you did not attach a copy
to the original return, check the appropriate box and attach a copy
of the federal form or schedule to this return. If you are ling this
return because of changes associated with federal Form 8886 or
federal Schedule M-3, Part II, Line 12, provide a detailed explanation
in the “Explain the changes on this return” area.
F — If you are a unitary company and completed Schedule UB,
check the box and attach Schedule UB to your return.
G — If you are a unitary company and completed Subgroup
Schedule, check this box and attach Subgroup Schedule. See
Subgroup Schedule Instructions for more information.
H —You must check the box and attach Schedule 1299-D, Income
Tax Credits (for corporations and duciaries), and any other required
support listed on Schedule 1299-D if you are entitled to take income
tax credits on Step 7, Line 48, of your Form IL-1120-X, even if the
amount is not changing from your original return, or if you have
earned credits in this tax year, but are unable to use them.
I — You must check the box and attach Form IL-4562, Special
Depreciation, if you are claiming special depreciation addition or
subtraction modications on Form IL-1120-X, even if the amounts are
not changing from your original return.
J — You must check the box and attach Schedule M, Other
Additions and Subtractions (for businesses), if you are claiming other
addition or subtraction modications on Form IL-1120-X, even if the
amounts are not changing from your original return.
K — You must check the box and attach Schedule 80/20,
Related-Party Expenses, if you are claiming related-party expense
modications on your Form IL-1120-X, even if the amounts are not
changing from your original return.
L — Check this box if you are a 52/53 week ler. A 52/53 week
ler is a scal ler with a tax year that varies from 52 to 53 weeks
because their tax year ends on the same day of the week instead of
the last day of the month.
M — Enter your entire federal employer identication number (FEIN).
If you are a unitary company, enter the FEIN of the designated agent.
N — Enter your North American Industry Classication System
(NAICS) Code. If you are unsure of your code, you can research the
information at www.census.gov/naics or www.irs.gov.
O— Enter your Illinois corporate le (charter) number assigned to
you by the Illinois Secretary of State. If you are ling a unitary return,
enter the corporate le (charter) number of the designated agent.
P — Check the appropriate box for the reason you are ling
this return. If you are amending due to a federal change, you
must check the appropriate box for partial agreed or nalized and
include the date of IRS nalization, which might not be the date the
federal amended return was led. Attach a dated copy of any federal
examining ocer’s report. If you do not provide this date or the
required attachments, you may be assessed penalties and interest.
Q — If you are ling Form IL-1120-X on or before the extended due
date, and wish to make the election to treat all income, other than
compensation, as business income for this tax year, check this box.
If you previously had nonbusiness income on Form IL-1120, Step
4, Lines 24 and 32, you must reduce these amounts to zero on this
Form IL-1120-X. Once made, the election is irrevocable. If you are
ling Form IL-1120-X after the extended due date of the original
return and did not make the election on your original return, you
cannot check this box.
R — Check the box if you must adjust your loss or loss carryover
due to Discharge of Indebtedness. For more information, see the
instructions for Line 36 and Schedule NLD or UB/NLD Instructions.
S — Check the box if you are a cooperative and completed
Schedule INL either to make a rst-time election for treatment of
income or to gure your patronage and nonpatronage income or loss,
or you are a real estate mortgage investment conduit (REMIC) that
completed Schedule INL to make an adjustment to Illinois income.
Attach Schedule INL to your tax return.
T — Check this box if you annualized your income on
Form IL-2220, Computation of Penalties for Businesses. Attach
Form IL-2220 to your tax return. If you are ling Form IL-1120-X after
the extended due date of the original return, you cannot check this
box. Late-payment penalty for underpayment of estimated tax is
based on the tax shown due on your original return.
U — Check this box only if you have sales into Illinois and you
are not required to allocate them because you are protected by
Public Law 86-272. Complete Steps 1 through 5 of Form IL-1120-X.
V — Check this box if you are ling this amended return to report
changes to your Illinois sales factor numerator due to the inclusion or
exclusion of throwback sales.
W — Check this box if you are ling this amended return to report
changes to your Illinois sales factor numerator due to the inclusion or
exclusion of double throwback sales.
Explain the changes on this return
The purpose of this area is to allow you to explain what specic
changes you are making to your Illinois tax return. You should
include all relevant information, including, but not limited to, changes
made to
• specic addition and subtraction modications,
• unitary membership or unitary status,
• the business income election,
Specic Instructions