If the driver who hit you had no insurance, carried too little, or drove off before you got a plate number, the coverage that pays your bills is often your own. Illinois builds that protection into every auto policy by law, so you almost certainly have it even if you never asked for it. The rules here are more generous than in a lot of states, but they come with a setoff that quietly shrinks your payout and deadlines that run on their own clock.
Chicago alone logged 109,112 reported crashes in 2025, and another 9,461 in January 2026.12 A meaningful slice of those involve drivers with no coverage or a bare-minimum policy, which is exactly the situation uninsured (UM) and underinsured (UIM) motorist coverage exists to handle.
Uninsured motorist coverage is required here
Illinois makes UM bodily injury coverage mandatory on every auto liability policy issued or renewed in the state.3 It has to be there at a minimum of $25,000 per injured person and $50,000 per crash, the same floor the state sets for liability insurance under 625 ILCS 5/7-203.43 The Illinois Department of Insurance describes UM plainly: it covers your bodily injury when you are hit by an at-fault driver who has no liability insurance, or by a hit-and-run driver.5 If you buy liability limits above the state minimum, your insurer generally writes your UM to match, unless you ask in writing for less.6
There is a property-damage side too. Insurers must offer uninsured motorist property damage coverage, and when you carry it, it pays the actual cash value of your vehicle up to your limit, subject to a maximum $250 deductible.3 Hit-and-run vehicles count as uninsured for both the injury and property sides of the coverage.3 Proving a hit-and-run usually starts with a police crash report, so request the Illinois crash report early. If your car lost market value even after solid repairs, that is a separate diminished value claim, not something UM property damage pays.
Underinsured coverage and the gap it fills
Underinsured motorist coverage is also mandatory in Illinois, and the statute ties it directly to your UM limits: your policy must include UIM in an amount equal to your uninsured motorist coverage.6 It answers a common problem. The driver who hit you has insurance, just not enough to cover what they did to you.
Here is how the Department of Insurance frames it: UIM pays the difference between your UIM limits and the at-fault driver's liability limits, when theirs are lower than yours.5 The statute defines an "underinsured motor vehicle" as one whose total bodily injury liability limits are less than your UIM coverage.6 That definition carries a catch worth understanding. If you carry only the 25/50 state minimum, your UIM at 25/50 does nothing against another minimum-limits driver, because there is no gap between their limits and yours. UIM only produces money when your own limits sit above the other driver's.56 To carry UIM below your bodily injury limits, you have to sign a written request for the lower amount.6
The setoff that shrinks your check
Illinois UIM is gap coverage, not an extra layer stacked on top, and the setoff is where people get surprised. Your UIM limit is reduced by the amounts you actually recover from the at-fault driver's bodily injury policy.6
A quick example. Say you carry 100/300 UIM and your injuries are worth $80,000. The driver who hit you had the 25/50 minimum, and their insurer pays its full $25,000. Your UIM does not add $100,000 on top. It fills the gap: your $100,000 limit minus the $25,000 already paid leaves up to $75,000 available, so you can recover the remaining $55,000 and reach your full $80,000 in damages. If your injuries had run past $100,000, your UIM limit would cap what you collect.
Stacking is not guaranteed
Illinois has no statute that lets you automatically stack UM or UIM limits across several vehicles on one policy or across separate policies. Neither 215 ILCS 5/143a nor 143a-2 requires it.36 Whether your limits combine or stay capped at a single vehicle's amount comes down to the anti-stacking language in your own policy, and Illinois courts enforce those clauses when they are written clearly. If you insure three cars, do not assume you have three times the UIM.
Deadlines and the arbitration clause
The clock on the underlying injury is two years from the crash date under 735 ILCS 5/13-202.7 A UM or UIM claim is technically a contract claim against your own insurer, but you still need to protect that two-year window, and your policy sets its own deadline for demanding arbitration, which is often shorter. Read that clause the week you get hurt, not the month before it expires.
Illinois routes most UM and UIM disputes to arbitration. Under 215 ILCS 5/143a, an arbitration award is binding up to $75,000 for bodily injury to one person and $150,000 for two or more people in one crash, or your policy limits, whichever is less.3 Above those numbers the award is not binding, and either you or the insurer can reject it and take the case to court.3
One more deadline protects your UIM claim when you settle with the at-fault driver. If you reach a tentative settlement, notify your UIM insurer. To keep its right to go after that driver, the insurer has to advance you a payment equal to the settlement within 30 days of getting your notice.6 The rule lets you accept a reasonable offer from the other side without forfeiting your own UIM coverage.
Property damage has a far longer window: five years from the crash under 735 ILCS 5/13-205.8
How your own share of fault changes the payout
Illinois uses modified comparative negligence with a 51% bar.910 Your recovery drops by your percentage of fault, and if you are found more than 50% at fault, you collect nothing.9 This matters for UM and UIM because your insurer effectively steps into the shoes of the driver who hit you, so it can argue your share of fault to reduce or defeat the claim, the same way that driver's own insurer could have.
Getting help
A UM or UIM claim puts you across the table from your own insurance company, which is now acting like the opposing party. If the numbers are significant, or your insurer disputes fault or the value of your injuries, you can find an Illinois attorney to handle the claim or the arbitration.
This is general information about Illinois law, not legal advice.
Sources
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thatcarhitme.com, Chicago Year-over-Year Crash Report 2025 vs 2024. https://thatcarhitme.com/crash-data/illinois/chicago/2025-annual-report
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thatcarhitme.com, Chicago Crash Report January 2026. https://thatcarhitme.com/crash-data/illinois/chicago/january-2026-report
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Illinois General Assembly, 215 ILCS 5/143a. https://www.ilga.gov/legislation/ilcs/fulltext?DocName=021500050K143a
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Illinois General Assembly, 625 ILCS 5/7-203. https://www.ilga.gov/legislation/ilcs/fulltext?DocName=062500050K7-203
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Illinois Department of Insurance, Auto Insurance Shopping Guide. https://idoi.illinois.gov/consumers/consumerinsurance/auto-insurance-shopping-guide.html
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Illinois General Assembly, 215 ILCS 5/143a-2. https://www.ilga.gov/legislation/ilcs/fulltext?DocName=021500050K143a-2
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Illinois General Assembly, 735 ILCS 5/13-202. https://www.ilga.gov/legislation/ilcs/fulltext.asp?DocName=073500050K13-202
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Illinois General Assembly, 735 ILCS 5/13-205. https://www.ilga.gov/documents/legislation/ilcs/documents/073500050k13-205.htm
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Illinois General Assembly, 735 ILCS 5/2-1116. https://www.ilga.gov/legislation/ilcs/documents/073500050K2-1116.htm
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Illinois Department of Insurance, Comparative Negligence. https://idoi.illinois.gov/consumers/consumerinsurance/comparative-negligence.html