Illinois paycheck calculator, 2026
Illinois applies a single flat rate to all taxable income, but the allowance structure is what actually moves the number: the IL-W-4 asks for basic and additional allowances separately, and each reduces taxable wages by a fixed annual amount. Because the rate is flat, allowances are the only lever. Our 2026 Illinois figures are still being cross-checked, so this page shows the rules and sources rather than an estimate.
The Illinois withholding rate, 2026
4.95%applied to taxable wages
Illinois works this out from a formula rather than a bracket table, so the amount withheld depends on what your state form says as well as what you earn. These are the steps the calculation actually takes:
- Subtract $2,925 per line 1 allowance and $1,000 per line 2 allowance
- Multiply annual taxable wages by 4.95%
Bonuses and supplemental pay
Illinois withholds supplemental wages — bonuses, commission, severance — at a flat 4.95%, separately from your regular salary. A bonus can therefore have a different amount withheld than the same money paid as salary, which is usually why a bonus arrives smaller than expected.
What the Illinois withholding form asks for
| Field | What it does | Where it appears |
|---|---|---|
| IL-W-4 line 1 allowances | Allowances for the taxpayer, spouse, and dependents claimed on line 1. | IL Form W-4, line 1 |
| IL-W-4 line 2 allowances | Additional allowances claimed on line 2; each reduces annual wages by $1,000. | IL Form W-4, line 2 |
Notes and caveats
- Illinois IL-700-T for 2026 specifies a $2,925 basic allowance and 4.95% rate.
- The latest NFC bulletin available in this session, NFC-25-1745409482, specifies the same 4.95% rate and $1,000 additional allowance but still lists the 2025 basic allowance of $2,850. The ruleset uses the current Illinois DOR amount and is flagged pending NFC confirmation.
Sources
Every figure on this page is transcribed from a published source and carries the date it was read. Where two sources disagree, the disagreement is recorded rather than resolved silently.
- Illinois Department of Revenue, 2026 IL-700-T Illinois Withholding Tax Tables — read 2026-07-19 · cross-checked against NFC-25-1745409482, Illinois State Income Tax Withholding
- basicAllowance — Illinois Department of Revenue, 2026 IL-700-T Illinois Withholding Tax Tables , How to Figure the Amount to Withhold · read 2026-07-19
- additionalAllowance — Illinois Department of Revenue, 2026 IL-700-T Illinois Withholding Tax Tables , Formula method · read 2026-07-19
This is an estimate of payroll withholding, not tax advice, and not a prediction of your final tax bill. Withholding is what your employer sends in during the year; what you actually owe is settled when you file.