Getting hit by a driver who has no insurance, or not nearly enough of it, is more common than most people expect. When it happens in Wisconsin, the coverage that ends up paying your medical bills is often your own. State law builds a floor of protection into every auto policy, and it also lets insurers add fine print that quietly shrinks what you actually collect. The gap between those two things is where Wisconsin drivers get surprised.
The general idea of how uninsured and underinsured coverage works is the same in every state. What follows is what Wisconsin does differently: the exact dollar figures and the fine print that trips people up.
Every Wisconsin policy already includes uninsured motorist coverage
Wisconsin is one of the states that makes uninsured motorist (UM) bodily injury coverage mandatory. Wis. Stat. § 632.32(4)(a)1. requires every auto liability policy on a vehicle registered or principally garaged here to carry UM limits of at least $25,000 per person and $50,000 per accident.1 You can't reject it, and it can't be stripped out to lower your premium the way optional coverages can.2
UM coverage steps in when the at-fault driver carried no liability insurance at all. It also applies to hit-and-run crashes, where the driver who injured you is never identified, according to the Wisconsin Office of the Commissioner of Insurance.2 One limit to keep in mind: UM pays for bodily injury only. It does not cover damage to your car.2 Vehicle damage is a separate property claim, and if your car lost resale value after the repair, that falls under a Wisconsin diminished value claim.
The minimum liability limits a Wisconsin driver has to carry are 25/50/10 under Wis. Stat. § 344.33(2): $25,000 for injury or death of one person, $50,000 per accident, and $10,000 for property damage.3 Those same 25/50 figures set the mandatory UM floor.2
Underinsured coverage is optional, and easy to lose by accident
Underinsured motorist (UIM) coverage is a different animal. It fills the gap when the at-fault driver does have insurance, just not enough to cover what you're owed. Wisconsin does not require it. Under Wis. Stat. § 632.32(4m), an insurer has to offer it to you only once, in writing, when it delivers the policy, and if you accept, the limits must be at least $50,000 per person and $100,000 per accident.4
Here's the part that catches people. Your acceptance or rejection of UIM doesn't have to be in writing, and the statute says the absence of a premium payment for UIM is conclusive proof that you rejected it.4 So if you never paid a separate premium for it, you don't have it, even if you assumed you did. Pull out your declarations page and look for a UIM line.
When you do carry UIM, it raises the bodily injury protection for you and your passengers up to the limit you bought, but only when the at-fault driver's liability limits are lower than your UIM limits.2 If you carry $100,000 in UIM and the other driver had only the $25,000 state minimum, UIM is what covers the difference.
The reducing clause is why your check is smaller than your policy limit
This is the Wisconsin rule that surprises people most. Wis. Stat. § 632.32(5)(i) lets an insurer write a "reducing clause" into the policy. It allows your UM or UIM limit for any one accident to be reduced by amounts paid by or on behalf of the person legally responsible, and by amounts paid or payable under worker's compensation or disability benefit laws.5
For UIM, that means your coverage doesn't stack on top of the at-fault driver's payment. It gets offset by it. Go back to that $100,000 UIM policy and a driver with $25,000 in liability coverage. With a reducing clause, you don't collect $100,000 on top of the $25,000. You get the $25,000 from the other driver's insurer, and your UIM brings you up to $100,000 total, so up to $75,000 more, not a full $100,000 more. Two people holding the "same" $100,000 policy can end up with very different recoveries depending on this one clause. The statute permits it but doesn't force insurers to use it, so the wording of your policy matters.
You can't stack coverage across your own vehicles
If you insure more than one car, you might assume the UM and UIM limits add up. In Wisconsin they usually don't. Wis. Stat. § 632.32(5)(f) lets a policy say that the limits on one vehicle can't be added to the limits on your other vehicles to raise the total available for a single accident.6 Three cars each carrying $50,000 in UM coverage does not add up to $150,000. This anti-stacking language is standard in Wisconsin policies.
Medical payments coverage
Medical payments (MedPay) coverage is optional. Insurers must offer it, but you don't have to buy it, and the smallest amount you can purchase is $1,000, under Wis. Stat. § 632.32(4)(bc) and the OCI consumer guide.72 MedPay pays medical or funeral expenses regardless of who was at fault, which helps while a UM or UIM claim is still being worked out.
Fault and reporting still shape your claim
A UM or UIM claim isn't automatic money. You still have to show the other driver was at fault, and Wisconsin's comparative negligence law can cut what you recover. Under Wis. Stat. § 895.045(1), you can recover only if your share of the fault was not greater than the other party's, and your award drops by your own percentage of fault.8 Cross 51% and you recover nothing. The OCI guide states the same standard.2
Reporting matters too. Under Wisconsin's Safety Responsibility Law, any crash that injures or kills someone or causes more than $1,000 in property damage must be reported, and you have to file a Driver's Report of Accident with the DMV within 10 days if police didn't investigate the scene.2 When you need the official crash report to support a claim, you can request it through the Wisconsin crash reports process.9
How long you have to act
Wisconsin deadlines are firm. A personal injury claim generally has to be filed within 3 years of the crash under Wis. Stat. § 893.54(1m)(a).10 If someone died, a wrongful death claim arising from a motor vehicle accident has to be brought within 2 years under § 893.54(2m).10
A UM or UIM claim is a contract claim against your own insurer, so timing can also turn on your policy's notice and cooperation terms, not just the statute. That's one more reason not to sit on it. Notify your insurer promptly and get advice before you sign any release. When the dollar figures are large or a reducing clause is in play, it's worth talking to an attorney who handles Wisconsin crash claims. You can find one here.
This is general information, not legal advice.
Sources
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Wis. Stat. § 632.32(4)(a)1., Wisconsin Legislature. https://docs.legis.wisconsin.gov/document/statutes/632.32(4)(a)1.
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Consumer's Guide to Auto Insurance, PI-057 (R 07/2025), Wisconsin Office of the Commissioner of Insurance. https://oci.wi.gov/Documents/Consumers/pi-057.pdf
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Wis. Stat. § 344.33(2), Wisconsin Legislature. https://docs.legis.wisconsin.gov/statutes/statutes/344/iii/33?view=section
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Wis. Stat. § 632.32(4m), Wisconsin Legislature. https://docs.legis.wisconsin.gov/document/statutes/632.32(4m)
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Wis. Stat. § 632.32(5)(i), Wisconsin Legislature. https://docs.legis.wisconsin.gov/document/statutes/632.32(5)
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Wis. Stat. § 632.32(5)(f), Wisconsin Legislature. https://docs.legis.wisconsin.gov/document/statutes/632.32(5)
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Wis. Stat. § 632.32(4)(bc), Wisconsin Legislature. https://docs.legis.wisconsin.gov/document/statutes/632.32
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Wis. Stat. § 895.045(1), Wisconsin Legislature. https://docs.legis.wisconsin.gov/statutes/statutes/895/i/045?view=section
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Crash Reports Portal, Wisconsin Department of Transportation. https://crashreports.wi.gov/
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Wis. Stat. § 893.54, Wisconsin Legislature. https://docs.legis.wisconsin.gov/statutes/statutes/893/v/54?view=section