Supporting Documents for Form IL-1040-X
Do not mail this page with your Form IL-1040-X.
(including net operating loss (NOL) deductions)
If you ﬁ le Form IL-1040-X because you ﬁ led a U.S. Form 1040X that resulted in
an overpayment or because you are claiming an NOL carryback deduction, you must wait to ﬁ le this form until you
receive a federal ﬁ nalization notice from the IRS stating that they have accepted your change either by paying a refund
or by ﬁ nal assessment, agreement, or judgment. Write the date the IRS notiﬁ ed you (not the date you ﬁ led your
U.S. Form 1040X) in the appropriate space in Step 1, Line E, and attach proof of federal ﬁ nalization as listed below.
a balance due, you must attach a copy of your U.S. Form 1040X as proof of federal ﬁ nalization. Write the date you ﬁ led
your U.S. Form 1040X and paid the tax due in the appropriate space in Step 1, Line E. Failure to provide this date could
result in an assessment of a late-payment penalty.
Proof of federal ﬁ nalization for U.S. 1040X overpayments and NOL carryback deductions includes a copy of the
notiﬁ cation you received from the IRS that they accepted your changes; e.g., a refund check, "Statement of Account,"
agreement, or judgment, and
a copy of your U.S. Form 1040X, if ﬁ led, or
a copy of your U.S. Form 1045, Application for Tentative Refund, including all pages of Schedules A and B, along with a
copy of your refund check, if you ﬁ led your federal amended return due to a NOL.
Proof of federal ﬁ nalization for U.S. 1040X underpayments is a copy of your U.S. Form 1040X.
If you do not have proof of federal ﬁ nalization, contact the IRS at 1 800 829-0922 to request a record of your account.
Attach the proper supporting documents, listed below, to your return.
If you changed any of the lines identiﬁ ed below and do not attach the required supporting documents to your return,
we may partially or totally deny your claim.
If you corrected:
U.S. Form 1040, 1040X, or 1045 (with any Schedules A
and B) if a NOL.
Federal adjusted gross income
Note: If your NOL may be carried to any later taxable year,
you must complete and attach U.S. 1045 Schedule B, even
if you did not ﬁ le a U.S. 1045 for this year.
U.S. Form 1040 Schedules C, E, and F, if ﬁ led, for loss
Schedule K-1-P or K-1-T, or any other notiﬁ cation that was
furnished to you for partnership, S corporation, estate, and
Proof of federal ﬁ nalization
Schedule M with amended ﬁ gures and any other required
support listed on Schedule M
U.S. Form 1040 or 1040A, Page 1
Federally taxed Social Security
Form W-2, if applicable
and federally taxed retirement plan income
Form 1099-R, RRB-1099, or SSA-1099, if applicable
U.S. Form 1040, Page 1
Illinois Income Tax overpayment included in
U.S. 1040, Line 10
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