Illinois State Income Tax Filing

Illinois income tax at a glance

Illinois taxes income at a single flat rate of 4.95%, which makes it one of the more predictable state returns to prepare: there is no bracket to land in and no marginal-rate calculation to run. The Illinois constitution requires a flat rate, so this is structural rather than a policy setting that shifts each session. Two features matter more than the rate itself. There is no standard deduction — Illinois uses a personal exemption instead, which is much smaller — so a larger share of your income is exposed than a federal comparison suggests. And Illinois excludes qualifying retirement income entirely, including distributions from 401(k) plans, IRAs and most pensions, which is genuinely unusual and makes the state considerably more favourable for retirees than the flat rate alone implies.

Illinois tax rates

Personal exemption

$2,925 single, $5,850 joint, $2,925 per dependent

Rates and thresholds as of January 1, 2026. State legislatures change these mid-year and several states index brackets annually — check against Illinois Department of Revenue before relying on a figure.

What to watch out for in Illinois

• The flat rate is required by the Illinois constitution. A 2020 ballot measure to permit graduated rates was rejected, so a move to brackets would need a constitutional amendment rather than ordinary legislation.
• The retirement income exclusion covers qualifying distributions from 401(k) and similar plans, IRAs and most pensions. It is subtracted on the Illinois return rather than applied automatically, so it has to be claimed.
• Illinois has reciprocity agreements with Iowa, Kentucky, Michigan and Wisconsin. Residents of those states working in Illinois generally pay tax only at home on those wages, and vice versa.
• Illinois grants a credit for income tax paid to other states, which matters for anyone working across the Chicago metropolitan area into Indiana or Wisconsin.

The flat rate makes the Illinois cost of your Indian income easy to work out — and it is unrelieved

Illinois begins from your federal adjusted gross income and then applies its own additions and subtractions. That has a direct consequence for anyone with Indian income: whatever the federal return has already pulled into adjusted gross income — NRO interest, rent from an Indian property, gains on Indian shares — arrives in the Illinois base by default, without anyone deciding it should.

And the Illinois credit for tax paid elsewhere does not reach it. The Schedule CR instructions list the qualifying jurisdictions as another US state, the District of Columbia, Puerto Rico, or a US territory or possession, and state that no credit is allowed for taxes paid to the federal government or to foreign countries or their political subdivisions. So the credit that helps a Chicago resident working in Indiana does nothing for the same person's fixed deposit in Bengaluru.

The one advantage of a flat rate is that the exposure is not a mystery. Because Illinois charges 4.95% regardless of bracket, the state cost of your Indian income is simply 4.95% of it, and the Indian tax already deducted at source reduces that by nothing. There is no bracket management to attempt and no threshold to stay under, which at least makes it a number you can plan around rather than discover.

The absence of a standard deduction sharpens it further. Illinois grants a comparatively small personal exemption instead, so there is very little to absorb an extra slice of income before the flat rate applies to all of it.

One genuinely open point: Illinois excludes qualifying retirement income, but whether an Indian EPF withdrawal or an Indian pension falls inside that exclusion is not clear-cut — the subtraction is framed around US plan types. The federal treatment of EPF is itself unsettled, so we do not state a position here. If this is your situation it needs looking at specifically rather than assumed either way.

Go deeper on the India side

These guides cover the federal treatment of Indian income and assets in detail. They apply wherever you live in the US — Illinois sits on top of them.

• The Foreign Tax Credit and Form 1116The mechanism that actually stops you being taxed twice — and it does not work evenly. NRE interest is fully taxable in the US with no credit at all, because India exempted it. Plus the April-March year mismatch nobody warns you about.
• FBAR and Indian Bank AccountsWhich Indian accounts are reportable on FinCEN Form 114 — savings, NRE, NRO, FCNR, fixed deposits, PPF, EPF, demat — how the $10,000 aggregate threshold really works, and why many F-1 students owe nothing at all.
• Indian Mutual Funds and the PFIC ProblemPFIC status turns on the US income and asset tests applied to the fund — tests a pooled vehicle holding securities will often meet. What that means for your SIPs, why the default regime is the punitive one, why the QEF election is usually closed to you, and how many Form 8621s you may owe.
• The India-US Tax TreatyIt does not stop the US taxing your Indian income — a saving clause preserves that. What the treaty really provides, why the foreign tax credit is the actual mechanism, and the one benefit that is unique to India.
• EPF, PPF and NPS on a US ReturnThe hardest topic in India-US filing, and the one where a confident answer should worry you. There is a Form 3520 exception almost nobody claims — and a timing question that is genuinely unsettled, so we set out the positions instead of picking one.

Forms and deadlines

Which form

Form IL-1040, with Schedule NR for non-residents and part-year residents

Deadline

Aligns with the federal deadline.

State authority

Illinois Department of Revenue

Federal deadlines are separate from state ones. Our US tax deadlines page covers the federal calendar, and the federal tax brackets apply on top of whatever Illinois charges.

Want the arithmetic done for you? The Illinois state tax calculator applies the schedule above to a salary and shows the result band by band.

Where these figures come from

Rates, bracket floors, standard deductions and exemptions are taken from the compilation below, stated as of January 1, 2026 and built from state statutes, forms and instructions. The state authority is always the final word on your own position.

• Tax Foundation — 2026 State Income Tax Rates and Brackets
• Illinois Department of Revenue

Reviewed by Teja K, CPA · last reviewed September 15, 2026. General information, not tax advice for your situation. State tax law changes frequently — confirm before acting. How we research and review this.