The rules
| Forms filed with the state | Form 1099-K (mandatory) and W-2G. 1099-R and 1099-MISC showing Illinois withholding may be filed voluntarily; all other 1099s (including NEC) not required unless IDOR requests them. |
| Who must file | 1099-K: any payer required by the IRS to e-file 1099-K, OR where the payee has 4+ transactions totaling over $1,000 (Illinois-payee rule). |
| Due date | 1099-K and W-2G: March 31 (Pub-110 R-01/26 states March 31, 2026 for tax year 2025). No Illinois deadline for voluntary 1099-R/MISC. |
| How | Electronic only: MyTax Illinois (CSV/manual, 1099-R/MISC only), MyTax Illinois non-login bulk upload (FIRE format), or Illinois FIRE Electronic Transmission Program (required for 1099-K). No paper option. |
| State 1099-K threshold | $1,000 and 4 or more transactions per payee (Pub-110). |
| Nonresident withholding | None on nonresident independent contractors; pass-through entity withholding only. No state backup-withholding rule. |
- CF/SF not mentioned by IDOR as satisfying the 1099-K mandate; direct electronic submission required.
- Pub-110 revised January 2026 covers 2025 returns due in 2026.
Questions people ask about Illinois
Do I have to file 1099s directly with Illinois?
Yes, when Illinois tax was withheld on the payment. Even without withholding, Illinois requires a direct filing in some cases. 1099-K: any payer required by the IRS to e-file 1099-K, OR where the payee has 4+ transactions totaling over $1,000 (Illinois-payee rule).
Which 1099 forms does Illinois require?
Form 1099-K (mandatory) and W-2G. 1099-R and 1099-MISC showing Illinois withholding may be filed voluntarily; all other 1099s (including NEC) not required unless IDOR requests them.
When are 1099s due in Illinois?
1099-K and W-2G: March 31 (Pub-110 R-01/26 states March 31, 2026 for tax year 2025). No Illinois deadline for voluntary 1099-R/MISC.
How do I file 1099s with Illinois?
Electronic only: MyTax Illinois (CSV/manual, 1099-R/MISC only), MyTax Illinois non-login bulk upload (FIRE format), or Illinois FIRE Electronic Transmission Program (required for 1099-K). No paper option.
Does Illinois have its own 1099-K threshold?
$1,000 and 4 or more transactions per payee (Pub-110).
Does Illinois require withholding on payments to nonresident contractors?
None on nonresident independent contractors; pass-through entity withholding only. No state backup-withholding rule.
Verified September 24, 2026 against https://tax.illinois.gov/research/publications/pubs/filing-and-storage-requirements-for-em…. Rules change annually and most states had not yet posted 2026 specifications at the time of review; confirm before filing.
What does not change by state
TIN matching, B-Notices, backup withholding and the IRC 6721 penalty are federal. A payee in Illinois who gives you a name/TIN pair that does not match IRS records produces the same CP2100 line as one anywhere else, and the same 15- and 30-business-day clocks. State filing is a separate obligation layered on top.