Illinois 1099-INT Filing Requirements, Tax Year 2026
What Illinois requires from businesses filing 1099-INT (Interest income) for tax year 2026: deadline, accepted format, CF/SF treatment, registration, and penalties, backed by primary-source citations.
Filing requirements
Illinois does not require a separate state filing of 1099-INT for tax year 2026. Federal filing satisfies the reporting obligation; no state submission is required.
Illinois does NOT require Form 1099-INT to be filed with the state when there is no Illinois income tax withheld. Per Pub-110 (R-01/26), 'All other Forms 1099 are not included in the electronic filing mandate nor are they required to be submitted to Illinois, unless we request them.' Illinois does not participate in the IRS Combined Federal/State Filing Program. If Illinois income tax was voluntarily withheld on interest, the payer may optionally file the 1099-INT through the Illinois FIRE Electronic Transmission Program; otherwise no Illinois filing is required.
Conditional rules
The summary above applies when no Illinois tax was withheld. The conditions below describe what changes when withholding is present, plus other scenario-specific rules:
| Condition | Explanation |
|---|---|
| Voluntary direct filing available when Illinois income tax was withheld |
If Illinois income tax was voluntarily withheld on a 1099-INT payment, the payer may (but is not required to) submit the 1099-INT to IDOR through the Illinois FIRE Electronic Transmission Program. Illinois withholding is also reported separately on quarterly Form IL-941. There is no Illinois annual reconciliation return, so the 1099-INT voluntary filing stands alone with no transmittal cover sheet. |
Deadlines and extensions
Extensions
Not applicable. Because 1099-INT is not required to be filed with Illinois, there is no state extension process.
Accepted format
No state filing is required for 1099-INT in Illinois, so no state-specific format applies.
Registration
Registration required: No
Late-filing penalties
Illinois penalty overview
Failure to e-file W-2/W-2c/W-2G: Per Pub-110 (R-01/26), '$5 penalty per Form W-2, W-2c, and W-2G' if filed without an approved Form IL-900-EW waiver. Pub-110 does not state a parallel per-form penalty for 1099-K outside the e-file mandate; standard withholding-tax penalty/interest provisions apply if Illinois income tax was withheld and reported incorrectly (see Pub-103). For all other 1099 series there is no Illinois filing mandate (and therefore no per-form Illinois penalty) unless IDOR specifically requests them.
Frequently asked questions
Does Illinois require filing of 1099-INT for tax year 2026?
Does Illinois participate in the CF/SF program?
What is the Illinois 1099-INT filing deadline for tax year 2026?
What format does Illinois accept for 1099-INT?
Do I need to file 1099-INT with Illinois if I also filed federally?
What happens if I miss the Illinois 1099-INT deadline?
Source citations
“All other Forms 1099 are not included in the electronic filing mandate nor are they required to be submitted to Illinois, unless we request them. Payers who issue Forms 1099 (not 1099-K) to individuals, which report Illinois income tax withheld, may voluntarily file these Forms 1099 electronically.”
“All other Forms 1099 are not included in the electronic filing mandate nor are they required to be submitted to Illinois, unless we request them. Payers who issue Forms 1099 (not 1099-K) to individuals, which report Illinois income tax withheld, may voluntarily file these Forms 1099 electronically through the Illinois FIRE Electronic Transmission Program or through MyTax Illinois.”
“Table 1: Participating States and Codes. State Code: Alabama 01, Arizona 04, Arkansas 05, California 06, Colorado 07, Connecticut 08, Delaware 10, District of Columbia 11, Georgia 13, Hawaii 15, Idaho 16, Indiana 18, Kansas 20, Louisiana 22, Maine 23, Maryland 24, Massachusetts 25, Michigan 26, Minnesota 27, Mississippi 28, Montana 30, Nebraska 31, New Jersey 34, New Mexico 35, North Carolina 37, North Dakota 38, Ohio 39, Oklahoma 40, Pennsylvania 42, Rhode Island 44, South Carolina 45, Wisconsin 55.”
“Payers who issue Forms 1099 (not 1099-K) to individuals, which report Illinois income tax withheld, may voluntarily file these Forms 1099 electronically through the Illinois FIRE Electronic Transmission Program or through MyTax Illinois.”
“Payers who issue Forms 1099 (not 1099-K) to individuals, which report Illinois income tax withheld, may voluntarily file these Forms 1099 electronically through the Illinois FIRE Electronic Transmission Program or through MyTax Illinois.”
Additional notes
Illinois has individual income tax but does NOT participate in the IRS Combined Federal/State Filing Program (CF/SF). Despite that, Illinois does NOT require most 1099s to be filed with the state. The single mandatory 1099 filing is Form 1099-K, which must be transmitted electronically through the Illinois FIRE Electronic Transmission Program by March 31 of the year following the tax year (for TY2025: March 31, 2026). All other 1099 forms (1099-INT, MISC, NEC, DIV, R, C, etc.) are not included in the electronic filing mandate and are not required to be submitted to Illinois unless IDOR specifically requests them. Payers may voluntarily submit other 1099s through MyTax Illinois (1099-R and 1099-MISC only) or the Illinois FIRE program if they wish to report Illinois withholding. There is no Illinois annual 1099 reconciliation return; withholding is reported quarterly on Form IL-941.
Scope: Original 1099 filings with no Illinois state income tax withheld. State agencies revise rules without notice; verify with the Illinois state agency directly before you file.
This page is general information only, not legal, tax, or accounting advice. You are solely responsible for verifying your filing obligations with the state agency or a qualified tax professional.
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