Connecticut does not let drivers quietly opt out of uninsured and underinsured motorist protection the way some states do. State law writes it into every auto liability policy automatically, and the amount you carry defaults to the same limit you picked for your own bodily injury liability.1 You can buy it down, but only by signing a specific form the Insurance Commissioner has to approve first.1 Police recorded 103,489 reportable crashes across Connecticut in 2025, and another 1,737 in March 2026 alone.23 In plenty of those wrecks the at-fault driver carries the state minimum or nothing at all, and this coverage is often the only money left to pay your medical bills.
The coverage is mandatory, and it tracks your liability limits
Under Conn. Gen. Stat. § 38a-336(a)(1)(A), every automobile liability policy issued in Connecticut has to include uninsured and underinsured (UM/UIM) coverage, with limits for bodily injury or death no lower than the state financial-responsibility floor.1 That floor is 25/50: $25,000 per injured person and $50,000 per accident, set by Conn. Gen. Stat. § 14-112(a).4
Since January 1, 1994, the default reaches higher than the floor. Your UM/UIM limits must equal the bodily injury liability limits you bought, unless a named insured asks in writing for a lower amount.1 Even then, the reduction is void unless you sign an informed-consent form approved by the Insurance Commissioner that lists your options and their premium costs and carries this warning in twelve-point type: "WHEN YOU SIGN THIS FORM, YOU ARE CHOOSING A REDUCED PREMIUM, BUT YOU ARE ALSO CHOOSING NOT TO PURCHASE CERTAIN VALUABLE COVERAGE WHICH PROTECTS YOU AND YOUR FAMILY."1 Insurers also have to offer you the choice of UM/UIM limits set at twice your bodily injury liability limits.1 The Connecticut Insurance Department repeats these rules in its consumer materials.5
What counts as an underinsured vehicle, and the reducing trap
Connecticut treats "uninsured" and "underinsured" as related but separate. For ordinary underinsured coverage, a car is underinsured when the at-fault driver's total bodily injury liability limits are lower than the UM limits on the policy you are claiming under.1
Here is the part that catches people off guard. Standard Connecticut UIM is "reducing" coverage. Your insurer only pays after the at-fault driver's liability limits are exhausted by settlement or judgment, and the total you collect from every policy combined cannot exceed your own UM/UIM limit.1 So if you carry $25,000 in UIM and the driver who hit you also carried $25,000, the $25,000 you recover from that driver already reaches your cap. Ordinary UIM then pays nothing on top. That offset, rather than the crash itself, is what leaves injured people short.
Conversion coverage changes the math
Connecticut created a second, better option that most drivers have never heard of. Under Conn. Gen. Stat. § 38a-336a, every insurer licensed here must offer underinsured motorist conversion coverage for an extra premium and describe it right alongside the informed-consent form.6 You buy conversion coverage in place of ordinary UIM, not on top of it.6
The difference is the offset. With conversion coverage, your underinsured limit is not reduced by anything the at-fault driver or a third party pays.6 It also uses a broader test for when a car is underinsured: the other driver counts as underinsured whenever the payments you receive from them fall short of your fair, just and reasonable damages, a wider standard than the limits comparison used for ordinary UIM.6
The numbers show why this matters. Say your damages come to $80,000, you carry $50,000 in coverage, and the at-fault driver had $25,000 in liability. Ordinary reducing UIM caps your total recovery at your own $50,000 limit, so after the $25,000 you collected from that driver, it adds only $25,000 more. Conversion coverage ignores the $25,000 the other driver paid and can pay up to its full $50,000 after you exhaust the other driver, taking you to $75,000. For a serious injury, that is the difference between a near-full recovery and a fraction of one.
The claim deadlines work differently
A UM/UIM claim is a contract claim against your own insurer, so it does not run on the ordinary two-year injury statute of limitations that governs a lawsuit against the at-fault driver under Conn. Gen. Stat. § 52-584.7 Instead, Conn. Gen. Stat. § 38a-336(g) sets a floor for the policy: no insurer may require you to sue or demand arbitration in less than three years from the date of the accident.1
Underinsured claims add a wrinkle, because you often cannot finish one until the at-fault driver's insurer pays out. The statute lets you toll (pause) the deadline if you do two things:1
- notify your insurer in writing of your underinsured claim before the limitation period runs out, and
- sue or demand arbitration within 180 days after the at-fault driver's bodily injury limits are exhausted by settlement or final judgment, appeals included.
A different rule covers a driver who was insured on paper but whose company later goes broke or denies the claim. That turns the loss into an uninsured claim, and your insurer cannot give you less than one year from the date you receive written notice of the insolvency or denial.1 Miss these windows and the coverage you paid for can disappear, so put them on the calendar early.
Other Connecticut rules worth knowing
Arbitration is common in these disputes, and the format depends on the money at stake. If the amount demanded is $40,000 or less, a single arbitrator decides it; above that figure, a panel of three does.1
You cannot stack. Connecticut bars adding together the UM/UIM limits of two or more vehicles, whether they sit on one policy or several.1 When you are hurt in a car you do not own, that car's policy pays first, your own policy is secondary, and any other applicable policies are excess.1
Your insurer cannot chase the at-fault driver for what it pays you. Conn. Gen. Stat. § 38a-336b prohibits any subrogation against the owner or operator of the underinsured vehicle for underinsured benefits.8
Certain money cannot be used to shrink your benefits. Your UM/UIM payout may not be reduced by Social Security disability benefits, and for policies issued or renewed on or after October 1, 2015, it also cannot be cut by what the at-fault driver paid other injured people or paid for property damage.1
Getting hurt on the job still counts. An employee injured while driving a covered vehicle in the course of employment is protected by that employer's UM/UIM, despite the usual workers' compensation exclusivity rule.1
Finally, you do have to make reasonable efforts to establish what coverage the other driver carried.9 But since October 1, 2006, your insurer cannot force you to produce a signed affidavit from the at-fault driver admitting they were uninsured or underinsured as a condition of paying you.9
After a Connecticut crash
UM/UIM here covers bodily injury, not your vehicle. If your car lost market value in the wreck, that is a separate property claim, and our Connecticut diminished value guide walks through it. To pull the official police report and see the underlying crash numbers, start with our Connecticut crash reports page. Because a UM/UIM claim puts you across the table from your own insurer, and because the reducing-versus-conversion distinction and the tolling deadlines are easy to get wrong, it is worth talking to a lawyer before you sign a release or let a clock run. You can find one through our legal directory.
This article is general information about Connecticut law, not legal advice.
Sources
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Conn. Gen. Stat. § 38a-336, Uninsured and underinsured motorist coverage. https://www.cga.ct.gov/current/pub/chap_700.htm#sec_38a-336
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thatcarhitme.com, Connecticut (Statewide) Crash Report, 2025. https://thatcarhitme.com/crash-data/connecticut/statewide/2025-annual-report
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thatcarhitme.com, Connecticut (Statewide) Crash Report, March 2026. https://thatcarhitme.com/crash-data/connecticut/statewide/march-2026-report
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Conn. Gen. Stat. § 14-112(a), Proof of financial responsibility. https://www.cga.ct.gov/current/pub/chap_246.htm#sec_14-112
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Connecticut Insurance Department, Auto Insurance consumer information. https://portal.ct.gov/cid/consumer-information-center/auto-insurance
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Conn. Gen. Stat. § 38a-336a, Underinsured motorist conversion coverage. https://www.cga.ct.gov/current/pub/chap_700.htm#sec_38a-336a
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Conn. Gen. Stat. § 52-584, Limitation of action for injury to person or property caused by negligence. https://www.cga.ct.gov/current/pub/chap_926.htm#sec_52-584
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Conn. Gen. Stat. § 38a-336b, Subrogation against owner or operator of underinsured motor vehicle prohibited. https://www.cga.ct.gov/current/pub/chap_700.htm#sec_38a-336b
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Conn. Gen. Stat. § 38a-336c, Claims for uninsured or underinsured motorist benefits. https://www.cga.ct.gov/current/pub/chap_700.htm#sec_38a-336c