Stock Option Advisor Match

Illinois Stock Options Tax: A Simpler Picture — But a Few Traps to Know

Illinois is neither a nightmare like California nor a tax haven like Texas. It has a flat 4.95% income tax on everything — ordinary income, short-term gains, long-term gains. No progressive brackets. No state AMT. No city income tax in Chicago. And Illinois conforms to the federal §1202 QSBS exclusion, unlike California.

Here's how Illinois compares on the issues that matter most to stock option holders:

Rule Illinois California New York
ISO exercise — state income tax? No — IL follows federal; no state income at exercise1 Yes — up to 13.3% as ordinary income at exercise No — NY follows federal
Long-term capital gains rate 4.95% — same flat rate as ordinary income2 13.3% — same as ordinary income Up to 10.9% — top bracket
QSBS (§1202) exclusion Yes — rolling conformity to §1202, 35 ILCS 5/1023 No — full gain taxable in CA regardless Yes — NY conforms to §1202
State AMT on ISOs? No — Illinois has no state AMT4 Yes — CA state AMT applies to ISO exercises No — New York has no state AMT
City income tax? None — Chicago has no city income tax5 No city income tax NYC: up to 3.876% city tax on NQSO spreads
LTCG preference? None — same 4.95% on all gains None — same 13.3% on all gains None — same rate on all gains

The summary: Illinois is meaningfully better than California on every front — and comparable to New York with a lower flat rate, no city tax, and a simpler rate structure. The main limitation is no long-term capital gains preference: qualifying ISO dispositions and multi-year hold strategies save nothing at the state level, even though they save substantially at the federal level.

Illinois Income Tax: The Flat Rate and the Personal Exemption

Illinois taxes all income — wages, interest, dividends, short-term capital gains, long-term capital gains — at a single flat rate of 4.95%.2 There are no tax brackets. The only structural offset is a personal exemption of $2,925 per taxpayer for tax year 2026 (inflation-adjusted annually).6

Income Type Illinois Rate Federal Rate (illustration, 37% bracket)
Wages / ordinary income 4.95% 37%
NQSO exercise spread (W-2 income) 4.95% 37% + FICA
ISO exercise spread (at exercise) 0% — no IL tax at exercise 0% ordinary (AMT preference item only)
ISO qualifying disposition (long-term gain) 4.95% 20% (+ 3.8% NIIT if applicable)
ISO disqualifying disposition — bargain element 4.95% 37%
Short-term capital gains (held ≤12 months) 4.95% — same as long-term 37%
Long-term capital gains (held >12 months) 4.95% — same as short-term 15–20%
QSBS gain excluded under §1202 0% — IL conforms to exclusion 0%

The critical implication for stock option holders: In Illinois, there is no financial benefit at the state level to holding ISO shares long enough to qualify for LTCG treatment. A qualifying disposition (held 2 years from grant, 1 year from exercise) and a disqualifying disposition are taxed at exactly the same Illinois rate — 4.95%. The qualifying disposition strategy is still worth pursuing for the federal tax savings (20% vs 37% on the bargain element), but the state decision is neutral. This is fundamentally different from California, where holding for qualifying disposition status makes little difference because everything is taxed at 13.3%.

ISO Treatment in Illinois: No State Tax at Exercise

Illinois computes taxable income starting from federal adjusted gross income (AGI).1 ISO exercises do not appear in federal AGI — they create an AMT preference item, not an AGI inclusion. As a result, Illinois does not impose ordinary income tax when you exercise an ISO. The state bill is deferred until you sell the shares, at which point it's capital gain taxed at 4.95%.

This is a direct contrast with California, which independently treats the ISO exercise spread as California ordinary income in the exercise year. In Illinois, you can exercise ISOs and owe no Illinois income tax until you sell — the same deferral the federal rules provide.

ISO qualifying disposition in Illinois

For an ISO qualifying disposition (shares held at least 2 years from grant date and at least 1 year from exercise date), the entire gain is a long-term capital gain for both federal and Illinois purposes. Illinois taxes that gain at 4.95%. Federal taxation is at the preferential LTCG rate (15–20% depending on income). The combined rate for a top-bracket Illinois resident on a qualifying disposition: roughly 24.95–28.95% (20% federal + 3.8% NIIT if applicable + 4.95% IL), compared to a disqualifying disposition at 41.95% or higher (37% federal + 4.95% IL). The federal rate difference is the dominant driver, not the state rate.

ISO disqualifying disposition in Illinois

If you sell ISO shares before the qualifying-disposition holding period is satisfied, you have a disqualifying disposition. The bargain element at exercise (FMV at exercise minus strike price, or the gain if less) becomes ordinary income — W-2 wages — taxed at 4.95% in Illinois. Any remaining appreciation above the exercise-date FMV is a capital gain, taxed at 4.95% regardless of how long you held the shares (since Illinois makes no distinction between short-term and long-term capital gains).

Example: disqualifying disposition at Relativity. You exercise 5,000 ISOs at $30 when FMV is $70 (spread = $200,000 bargain element). You sell 6 months later at $80.
  • Bargain element: $200,000 — W-2 ordinary income. IL tax: $200,000 × 4.95% = $9,900
  • Remaining gain: ($80 − $70) × 5,000 = $50,000 — short-term capital gain. IL tax: $50,000 × 4.95% = $2,475
  • Total Illinois tax: $12,375
  • Federal comparison: $200,000 bargain element at 37% = $74,000; $50,000 short-term gain at 37% = $18,500 — plus FICA on the W-2 piece

Illinois is a predictable 4.95% on whatever the federal definition of income is. The volatility in your combined tax bill comes from the federal side, not the state side.

NQSO Treatment in Illinois

Nonqualified stock options follow the same straightforward logic. The spread at exercise is W-2 ordinary income subject to FICA and federal income tax at the federal level; in Illinois, it's included in your IL base income and taxed at 4.95%.

When you later sell the shares, any appreciation above the exercise-date FMV is capital gain — taxed at 4.95% in Illinois regardless of the holding period (no distinction between short-term and long-term at the state level).

Example: NQSO exercise at Motorola Solutions. You exercise 8,000 NQSOs at $40, FMV = $90. Spread = $400,000.
  • At exercise (W-2 income): $400,000 × 4.95% = $19,800 Illinois income tax (employer should withhold at state supplemental rate)
  • Federal W-2 income: $400,000 × 37% = $148,000 federal; plus $6,200 FICA on $184,500 SS wage base amount not yet earned (2026 SS wage base: $184,5007); plus 1.45% Medicare + 0.9% Additional Medicare on earnings above $200,000
  • When you sell (at $110, 9 months later): ($110 − $90) × 8,000 = $160,000 gain. IL tax: $7,920 — same whether you hold 9 months or 2 years.

QSBS in Illinois: The Major Advantage Over California

Illinois uses rolling conformity to the Internal Revenue Code under 35 ILCS 5/102.3 This means that as the federal IRC is amended, Illinois automatically adopts the changes — including §1202 (Qualified Small Business Stock). Illinois residents can exclude the same QSBS gain from Illinois income that they exclude at the federal level.

What this means vs. California

California explicitly decouples from §1202 — California Revenue & Taxation Code §18152.5 provides that California does not conform to the federal QSBS exclusion. A California resident with $15M of QSBS gain pays California tax on the entire $15M at 13.3%: $1,995,000 to California, on top of whatever federal tax applies to non-excluded gain.

An Illinois resident with the same $15M gain (fully excluded under OBBBA's 5-year 100% exclusion) pays $0 to Illinois on the excluded portion. The difference in state tax alone is nearly $2M on the same transaction.

QSBS thresholds under OBBBA (post-July 2025)

The One Big Beautiful Bill Act (OBBBA, signed July 4, 2025) made significant changes to §1202 for stock acquired on or after July 5, 2025:8

Because Illinois uses rolling conformity, the OBBBA-expanded §1202 parameters should apply to Illinois-resident taxpayers. However, Illinois separately decoupled from OBBBA's bonus depreciation provisions — meaning the OBBBA adoption is selective. Verify with an Illinois tax advisor whether the §1202 OBBBA amendments have been specifically incorporated before relying on the $15M cap or $75M gross-asset threshold at the state level.3

QSBS comparison: Illinois vs California on a $12M startup gain. A Tempus or Relativity early employee exercises options (83(b) election at founding), holds 5+ years post-OBBBA, sells for $12M gain — well within the $15M OBBBA cap.
  • Federal: $12M fully excluded (100%, 5-year hold). Federal tax: on any non-QSBS basis only.
  • Illinois: $12M excluded from IL income (rolling §1202 conformity). Illinois tax on this gain: $0.
  • California: $12M fully taxable at 13.3%. California tax: $1,596,000.

The QSBS advantage in Illinois vs California is the single most important state-level distinction for startup founders and early employees with qualified stock.

The 28% federal rate trap on partial QSBS exclusions

A technical point that Illinois residents also face: for stock acquired before September 28, 2010 (100% exclusion was not available), or for gain that exceeds the per-issuer cap, the non-excluded portion is subject to a 28% alternative federal capital gains rate. Illinois taxes its 4.95% share of whatever is included in the federal base — so this trap is primarily a federal-level issue, but you will owe Illinois tax on the included amount.

No State AMT: How This Helps Illinois ISO Holders

Illinois does not have a state alternative minimum tax.4 When you exercise ISOs, you may owe federal AMT — but there is no additional Illinois AMT layer on the ISO spread. This stands in contrast to California, which has its own state AMT that can add several percentage points to the cost of exercising ISOs in a single year.

The federal AMT parameters for 2026: $90,100 exemption (single filer) / $140,200 (MFJ), with phaseout beginning at $500,000 / $1,000,000 at the OBBBA-restored 50% rate.9 Use the ISO AMT Calculator linked below to model your federal exposure; your Illinois bill on the same exercise is simply zero (no state income tax at exercise at all).

No Chicago City Income Tax

Chicago does not impose a city income tax.5 Compare this to New York City, which adds up to 3.876% city income tax on top of the New York State rate — and that city tax applies to NQSO exercise spreads, qualifying and disqualifying ISO dispositions, and RSU vesting. For a Chicago tech employee, the combined state + local rate on stock option income is a flat 4.95%, full stop. For an equivalent NYC employee, the combined state + city top rate is approximately 14.776%.

Chicago does impose other local taxes (property tax, sales tax, lease tax), but none of these apply to stock option income.

Nonresident Sourcing: Illinois Claims Options Earned in Illinois

If you received stock option grants while working in Illinois and have since moved to another state, Illinois may still claim a portion of the exercise income as Illinois-source income when you exercise.10 The sourcing rule works like this:

IL-source income = exercise spread × (Illinois workdays from grant to exercise ÷ total workdays from grant to exercise)
Example: Moving from Chicago to Texas. You received an NQSO grant in January 2023 while at a Chicago-based firm. You relocated to Austin in June 2025. You exercise in March 2026.
  • Grant to exercise period: January 2023 – March 2026 = ~38 months
  • Illinois workdays: January 2023 – June 2025 = ~29 months
  • Sourcing ratio: 29 / 38 = 76%
  • Exercise spread: $300,000
  • IL-source income: $300,000 × 76% = $228,000 — taxable to Illinois as a nonresident
  • Illinois tax due: $228,000 × 4.95% = $11,286 (filed as IL nonresident return)

Texas has no state income tax, so there's no credit to offset the Illinois bill. The sourcing ratio erodes gradually the longer you wait to exercise after moving. An advisor can model whether waiting another year to exercise meaningfully reduces the Illinois exposure.

Moving from Illinois to a state with income tax

If you move from Illinois to a state that imposes its own sourcing rules — California and New York are the most aggressive — both states may assert the right to tax the exercise spread. Illinois taxes the IL-sourced share; your new home state taxes the full spread, with a credit for Illinois tax paid. Whether the credit fully offsets depends on the states involved. Double-taxation risk is highest when moving to California (which uses its own workdays-ratio sourcing) and when exercising options granted before the move. A multi-state specialist should model this before you pull the trigger.

Former Illinois residents: the residency trap

Illinois Private Letter Ruling IT-94-0035 established that if you are an Illinois resident when you exercise NQSOs, Illinois taxes 100% of the spread — even if the options were partially earned while you were a resident of another state.10 The flip side is also true: if you move out of Illinois before exercising, the sourcing rule reduces your Illinois exposure. The key date is when the exercise occurs, not when the options were granted.

Six Planning Strategies for Illinois Stock Option Holders

1. Time ISO exercises in low-income years to manage federal AMT — not state tax

Because Illinois has no state AMT and no state income tax at ISO exercise, the only decision driver for exercise timing in Illinois is the federal AMT. This simplifies the planning: identify the year(s) where your federal AMTI is lowest, exercise ISOs up to the federal AMT safe zone (roughly: spread amount that leaves you paying zero federal AMT on the exercise), and there's no Illinois component to worry about at exercise. The calculator below models the federal side.

2. QSBS: maximize early-exercise + 83(b) opportunities at qualifying IL startups

Illinois conforms to §1202, which means early-exercising options at an Illinois-based startup, filing an 83(b) election, and holding 5 years can result in $0 Illinois state tax on up to $15M of gain (per OBBBA — verify current IL OBBBA conformity with an advisor). The 83(b) election starts the §1202 holding clock at the exercise date, not the vesting date. For a founder or early employee at a company like Tempus, Relativity, or a Chicago-area startup under $75M gross assets, this stacking strategy can eliminate a combined 5–20%+ state + federal tax bill on the qualifying gain.

3. Don't over-optimize holding periods for Illinois purposes

In California, the lack of LTCG preference means the qualifying-disposition strategy adds no state benefit — but it costs you nothing either (same rate). In Illinois, the logic is the same: there's no state tax savings from holding for qualifying-disposition status (4.95% whether qualifying or disqualifying on the capital gain portion). Plan your holding period purely for federal tax optimization. If selling ISO shares before the 1-year exercise anniversary makes sense for diversification or AMT management, the Illinois bill is the same either way.

4. Sequence NQSO exercises to stay below the SS wage base

The 2026 Social Security wage base is $184,500.7 NQSO exercise spread is W-2 wages and triggers Social Security tax (6.2%, employer + employee match) until you hit the annual cap. If your regular salary already exceeds the wage base, NQSO exercises in the same year avoid the 6.2% SS tax — you only pay 1.45% Medicare (+ 0.9% Additional Medicare on wages above $200,000). Sequencing exercises into the second half of the year, after salary has exhausted the SS wage base, is a straightforward way to save 6.2% on large NQSO spreads. Illinois doesn't change this math — it's a federal benefit — but it's often overlooked in the state-focused planning conversation.

5. Model the sourcing ratio before exercising if you recently moved out of Illinois

If you left Illinois in the last 1–3 years and still hold unexercised grants from your Illinois employment, calculate your current sourcing ratio before exercising. If you have a $500,000 NQSO spread and your sourcing ratio is 70%, you owe Illinois $17,325 on the nonresident return. Wait 12 more months post-relocation, and the ratio may drop to 60%, saving $4,950 in Illinois tax. Whether the savings justify the timing decision depends on your specific numbers and whether you believe the stock price holds. An advisor can run the exact model.

6. Charitable giving with appreciated shares: the Illinois angle

After exercising ISOs and holding for qualifying-disposition status, you have shares with long-term capital gain built in. Donating appreciated shares directly to a donor-advised fund (DAF) avoids the capital gains at the federal level and gets you a charitable deduction for the fair market value. In Illinois, this is doubly beneficial: you avoid the 4.95% Illinois capital gains tax on the donated shares, and Illinois allows a deduction for charitable contributions based on your federal deduction (with some modifications). For post-IPO tech employees with large appreciated stock positions and charitable intent, this strategy can eliminate the Illinois capital gains bill entirely on the donated portion.

Related guides and tools

Get matched with an Illinois stock option advisor

Illinois stock option planning is simpler than California — but it still involves coordinating federal AMT (at ISO exercise), Illinois sourcing (if you've recently moved), QSBS eligibility (if you hold startup stock), and NQSO exercise timing against the SS wage base. A specialist who handles Illinois equity compensation regularly will find planning angles a generalist will miss. Free match, no obligation.

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  1. Illinois ISO treatment — no ordinary income at exercise. Illinois computes taxable income by starting from federal AGI under 35 ILCS 5/203. Because ISO exercises do not create federal AGI (the exercise spread is an AMT preference item, not an AGI item), Illinois imposes no state income tax at ISO exercise. Confirmed via Illinois Income Tax Act structure and Illinois income tax conformity analysis (RemoteLaws 2026); contrast with California FTB Publication 1004 which overrides federal ISO deferral with CA ordinary income treatment at exercise.
  2. Illinois flat income tax rate: 4.95% on all income including capital gains. No long-term capital gains preference — short-term and long-term gains taxed identically. Illinois Constitution Art. IX §3 prohibits graduated income tax rates (the Graduated Income Tax Amendment was rejected by Illinois voters in November 2020, confirming the flat rate structure). Sources: Illinois Department of Revenue FY 2026-15; SmartAsset 2026 Capital Gains Tax Rates by State; Tax Foundation Illinois income tax overview.
  3. Illinois §1202 QSBS conformity: Illinois uses rolling conformity to the federal IRC under 35 ILCS 5/102, meaning federal IRC changes are automatically adopted unless Illinois specifically decouples. Illinois conforms to §1202 QSBS exclusion — confirmed via QSBS Expert: Illinois QSBS Treatment and Keystone Global Partners QSBS by State 2026. Note: Illinois selectively decoupled from OBBBA's bonus depreciation provisions in 2026; verify whether OBBBA-expanded §1202 thresholds ($15M cap, $75M gross assets) are specifically incorporated into Illinois law before relying on them for planning — per State OBBBA Conformity Status 2026 (Marble.ai).
  4. Illinois has no state alternative minimum tax. AMT is a federal mechanism only in Illinois. Confirmed via absence of any state AMT provision in Illinois Income Tax Act (35 ILCS 5/); cross-checked with Tax Foundation Illinois state tax profile. States with their own state AMT include California, Colorado, Iowa, and Minnesota; Illinois is not among them.
  5. Chicago has no city income tax. Unlike New York City (up to 3.876% city income tax), San Francisco (gross receipts-based business tax, not personal income), or Philadelphia (3.75% wage tax), Chicago does not impose a personal income tax at the city level. Source: Chicago Municipal Code; confirmed via Illinois Department of Revenue guidance that the only Illinois income tax is the state-level flat 4.95% under the Illinois Income Tax Act.
  6. Illinois personal exemption for 2026: $2,925 per taxpayer. Illinois adjusts the personal exemption for inflation annually. 2024 was $2,775; 2025 was $2,850; 2026 per IRS inflation-adjustment precedent and Illinois DOR FY 2026-15 bulletin. Source: Illinois Department of Revenue FY 2026-15.
  7. 2026 Social Security wage base: $184,500. Confirmed per SSA.gov announcement for tax year 2026. NQSO exercise spreads are FICA wages subject to 6.2% SS (employer + employee) up to this limit, plus 1.45% Medicare on all wages, plus 0.9% Additional Medicare on wages above $200,000 (single). Source: SSA.gov — Contribution and Benefit Base 2026.
  8. OBBBA §1202 changes (July 4, 2025): gross asset limit raised from $50M to $75M; per-issuer exclusion cap raised from $10M to $15M; tiered exclusions 50%/75%/100% at 3/4/5-year hold. Applies to stock acquired on or after July 5, 2025. Prior-track stock (pre-July 5, 2025) remains subject to old $50M/$10M limits but retains 100% exclusion at 5 years for post-September 27, 2010 acquisitions. Sources: Foley & Lardner OBBBA §1202 Analysis; Michael Best OBBBA QSBS Expansion.
  9. 2026 federal AMT parameters: exemption $90,100 (single) / $140,200 (MFJ); phaseout begins at $500,000 (single) / $1,000,000 (MFJ); OBBBA restored phaseout reduction rate to 50% on AMTI over the threshold. AMT tax rates: 26% on first $244,500 of AMTI; 28% above. Sources: IRS Rev. Proc. 2025-67 (inflation adjustments); confirmed via SmartAsset 2026 AMT Brackets.
  10. Illinois nonresident sourcing of stock option income. Illinois sources NQSO and RSU income for nonresidents using a workdays-ratio allocation based on Illinois workdays during the grant-to-exercise period. For Illinois residents at exercise, 100% of NQSO spread is Illinois-source income under the Illinois Income Tax Act §203(a) and the principle established in Illinois Department of Revenue Private Letter Ruling IT-94-0035 (resident taxed on full exercise value regardless of where options were earned). Sources: Wipfli: State Income Tax Implications for Deferred Compensation; Phoenix Strategy Group: State Tax Rules for Nonresident Equity Compensation.

Values verified May 2026. Tax law changes frequently; confirm current-year values with a qualified Illinois tax advisor before making irreversible decisions.