This guide covers the 2027 tax year, which is generally filed in 2028. As of late 2026, the Illinois Department of Revenue (IDOR) has not published a 2027 IL-1040 or Schedule M. Figures below are labeled by the year they come from, so confirm every threshold, credit amount, form, and deadline against current IDOR and IRS materials before filing.
We'll cover eligibility, the major Illinois tax reductions, the calculation, documentation, and where Illinois departs from federal rules.
Key Takeaways
- Illinois has no separate state standard deduction line. Use exemptions, subtractions, and credits instead.
- Subtractions reduce taxable income; credits reduce the tax itself and may be refundable or nonrefundable.
- Residency, filing status, income type, and federal AGI all affect eligibility.
- Confirm 2027 amounts in the final IL-1040 instructions before you file.
Illinois Deductions, Exemptions, Subtractions, and Credits: What Each Means
The four terms in plain language
- Deduction: an expense that reduces income before tax. Illinois largely doesn't offer these in the federal sense.
- Subtraction: an amount removed from federal AGI because Illinois doesn't tax it, such as qualifying retirement income.
- Exemption allowance: a fixed amount per qualifying person that reduces income before the rate applies.
- Tax credit: a dollar-for-dollar reduction of the tax you owe.
The calculation sequence
The return follows a predictable order:
- Start with federal AGI.
- Add items Illinois requires you to add.
- Subtract items Illinois allows (IL-1040 lines for retirement income, plus Schedule M).
- Arrive at Illinois base income.
- Apply the exemption allowance.
- Multiply the remainder by the flat rate.
- Apply credits, then compare against withholding and payments.
Illinois versus the federal return
Federal itemized deductions on Schedule A do not carry over. IDOR says Illinois subtractions must be specifically authorized on Schedule M or another Illinois form. A taxpayer who itemizes federally gets no automatic benefit on the state return.
The federal SALT deduction is a separate matter. For 2025, the IRS Schedule A instructions set a $40,000 cap ($20,000 for married filing separately). Under 26 U.S.C. §164, the cap rises 1% a year, which works out to roughly $40,804 for 2027.
Check IRS guidance for the final number. Either way, it's a federal itemized deduction and creates no Illinois subtraction.
Why identical incomes produce different bills
Take two people earning $100,000 in gross income. One is single with wages only. The other is a retiree with Social Security, a pension, and a dependent spouse.
Their Illinois base income, exemptions, credits, and withholding all differ, so their tax differs too. Any "universal" result is misleading.
Major Illinois Tax Deductions and Subtractions for 2027
Personal exemption allowance
IDOR states the personal exemption is $2,925 per exemption for tax year 2026. IDOR has not published a 2027 amount yet, so use $2,925 only as a working estimate until the official figure is released.
Under the TY2026 rules:
- Age 65 or older and legal blindness each add a $1,000 allowance.
- No exemption is allowed if federal AGI exceeds $250,000 ($500,000 for married filing jointly).
- A person who can be claimed as someone else's dependent generally gets the allowance only if their Illinois base income is $2,925 or less.
Schedule M subtractions
Schedule M is where most Illinois-specific subtractions live. Use the 2027 version, not older lists. The TY2025 form shows the likely categories:
- Illinois college savings: contributions to Bright Start, Bright Directions, or College Illinois, up to $10,000 ($20,000 joint). Other states' plans are excluded.
- ABLE accounts: contributions to a qualified Illinois ABLE account, with the same $10,000/$20,000 limits.
- Military pay: qualifying U.S. Armed Forces and National Guard pay, with exclusions.
- Other items: qualifying medical-debt-relief income, Illinois special depreciation, U.S. government interest, certain bond interest, ridesharing benefits, railroad sick pay, and pass-through adjustments.
Retirement and exempt income
Eligible Social Security and retirement-plan income, including Illinois Teachers' Retirement income, is subtracted on IL-1040 line 5 (per the 2025 form). This is not a Schedule M item; treating it as one is a common mistake.
Why does the income show up at all? Federal forms often include it in AGI. Illinois then removes it through the subtraction. Pensions, IRA distributions, and annuities each have their own conditions, so read the 2027 instructions line by line.
Business and self-employment income
Ordinary business expenses are handled on the federal schedule or return, such as Schedule C, and flow into the starting AGI. Illinois additions and subtractions are then reviewed separately.
Owners of partnerships and S corporations should keep entity-level deductions distinct from personal Illinois adjustments. If the entity operates in several states, get professional review. Apportionment and credit questions multiply fast.
Illinois Tax Credits That May Reduce Your 2027 Tax
Illinois Earned Income Credit
The Illinois credit is generally 20% of the federal EITC, and per IDOR Publication 132 it may result in a refund. Illinois eligibility tracks the federal credit but isn't identical. For example, IDOR identifies exceptions involving qualifying children with ITINs.
Gather the same records you'd use for the federal EITC: income statements, qualifying-child details, and Social Security numbers. Then read IDOR's own filing rules, since documentation requirements can differ. The 20% figure is TY2025 guidance; check the 2027 rate.
Education-related credits
The K-12 Education Expense Credit (TY2025 guidance) works like this:
- 25% of qualified expenses above the first $250
- Maximum $750 per return
- Applies to Illinois public or nonpublic K-12 schools
- Student must be under 21 at the close of the school year
- Taxpayer and student must be Illinois residents when expenses are paid
- No credit if federal AGI exceeds $500,000 (joint) or $250,000 (others)
Preschool and college costs don't qualify. The credit is nonrefundable.
Property-tax and family-related credits
Property Tax Credit. TY2025 instructions give 5% of Illinois real estate taxes paid on an owned principal residence in Illinois, with the same AGI cutoffs as above. It's nonrefundable.
Child Tax Credit. Under 35 ILCS 5/244, the credit applies to a qualifying child under 12. For tax years beginning on or after January 1, 2025, it equals 40% of the Illinois EITC.
The statute shows no sunset, but IDOR's public page describes the program as created for 2024 and 2025. Check that status before you count on the credit for 2027. Ask IDOR whether it is refundable, since neither the statute nor IDOR's page states refundability.
Refundable versus nonrefundable
A nonrefundable credit, such as those on Schedule ICR, can only reduce your tax to zero. If you owe $400 and have a $750 education credit, you lose the unused $350. A refundable credit, such as the Illinois EITC, can generate a refund beyond what you owe.
Who Can Claim Illinois Tax Benefits?
Residents, part-year residents, and nonresidents
- Residents are taxed on income from all sources, wherever earned.
- Part-year residents report all income from the residency period plus Illinois-source income received as a nonresident.
- Nonresidents are taxed only on Illinois-source income. Business or farm income may be apportioned by Illinois sales relative to total sales.
Part-year and nonresident filers use Form IL-1040 with Schedule NR. They allocate income and adjustments rather than applying every benefit against all income.
Reciprocity and multi-state situations
Illinois has wage reciprocity with Iowa, Kentucky, Michigan, and Wisconsin. Residents of those states working in Illinois are generally exempt from Illinois tax on wages, salaries, tips, and commissions. They give their employer Form IL-W-5-NR to stop Illinois withholding.
Reciprocity does not cover other Illinois income, such as lottery, gambling, or sports-wagering winnings.
Remote workers and commuters should weigh where they live, where they physically work, the source of the income, and how the employer reports it.
A Wisconsin resident who commutes to Chicago is covered. A New York resident working remotely for an Illinois employer from home generally is not an Illinois-source case, but confirm with current rules.
Filing status and special situations
- Single, joint, separate, head of household: exemption counts and AGI cutoffs differ. Joint filers get higher thresholds.
- Dependents: exemption is limited.
- Retirees: retirement and Social Security subtractions matter most.
- Military: qualifying pay may be subtracted.
- Self-employed: the starting AGI already reflects business expenses.
A full-year resident generally files if required to file federally or if Illinois base income exceeds the exemption allowance. Nonresidents and part-year residents may also file just to claim a refund of Illinois withholding.
How to Claim Illinois Deductions and Prepare for Filing
Forms and reporting steps
Download these forms from IDOR's site in their 2027 versions:
- IL-1040: main return, exemptions, and retirement subtractions
- Schedule M: other additions and subtractions
- Schedule ICR: nonrefundable credits
- Schedule IL-E/EIC: earned income credit
- Schedule NR: nonresident and part-year allocation
- IL-W-5-NR: reciprocity exemption from withholding
Follow these steps:
- Gather federal AGI figures from your completed federal return.
- Complete Illinois additions and subtractions on the relevant schedules.
- Claim the exemption allowance on Form IL-1040.
- Compute tax and apply any nonrefundable or refundable credits.
- Reconcile withholding and estimated payments against tax due.
- Submit payment or claim your refund with the return.
Estimating tax on $100,000 of income
The answer depends on whether $100,000 is gross income, federal AGI, or Illinois base income, plus filing status, exemptions, and credits. Here's one illustration with labeled assumptions:
| Assumption or step | Amount |
|---|---|
| Single filer, Illinois base income | $100,000 |
| One exemption (TY2026 amount) | −$2,925 |
| Net income | $97,075 |
| Rate (4.95%, per IDOR's rate page) | × 4.95% |
| Tax before credits | about $4,805.21 |
This assumes no other adjustments or credits. It is not a 2027 estimate or personal advice, since the 2027 exemption and rate could differ. It also covers state income tax only, not federal, local, payroll, or sales taxes.
Documentation and professional review
Keep these on hand:
- W-2s and 1099s
- Retirement and Social Security statements
- Proof of K-12 education expenses
- Property-tax bills and payment records
- Dependent information
- Credit documentation, including EITC details
- Schedule M records, such as 529 or ABLE contribution statements
- Schedule NR income allocation details, if applicable
If your return involves multiple states or cross-border income, professional review pays for itself.
VJM Global prepares U.S. individual returns (Form 1040 and 1040-NR) and supports cross-border tax compliance, accounting, and advisory work for U.S. businesses, foreign investors, and multinational companies. Reach out if Illinois obligations sit alongside international ones.
Frequently Asked Questions
How much tax will I pay on $100,000 in Illinois?
It depends on Illinois base income, filing status, exemptions, credits, and income source. At the current 4.95% flat rate, a single filer with $100,000 of base income and one exemption owes roughly $4,800 before credits. That figure excludes federal, local, payroll, and sales taxes.
What deductions and exemptions are available for Illinois state taxes?
Illinois offers a personal exemption allowance, subtractions for items like retirement income, qualifying 529 and ABLE contributions, and certain military pay, plus credits. Confirm the 2027 amounts in IDOR's final instructions.
Does Illinois have a standard deduction for 2027?
No separate standard deduction line appears on the published 2025 IL-1040. Illinois uses the personal exemption allowance instead. Check the 2027 IL-1040 instructions for current amounts.
What is the difference between an Illinois tax deduction and a tax credit?
Deductions and subtractions reduce the income that gets taxed. Credits reduce the calculated tax itself. Credits may be refundable (like the Illinois EITC) or nonrefundable (like Schedule ICR credits).
Who needs to file an Illinois state tax return?
Full-year residents generally file if they must file federally or if Illinois base income exceeds the exemption allowance. Part-year residents and nonresidents file when they have Illinois-source income above the threshold, or to claim a refund of withheld Illinois tax.
Can nonresidents and part-year residents claim Illinois tax deductions?
Often yes, but only in proportion to Illinois-source income or the residency period. Schedule NR handles the allocation, and eligibility varies by benefit.
