How Underinsured Motorist Claims Work in Missouri

In Missouri, an underinsured motorist (UIM) claim lets an injured person seek additional compensation from their own auto insurer when the at-fault driver has liability insurance but not enough to cover the full loss. Missouri requires uninsured motorist coverage on every auto liability policy, but underinsured motorist coverage is generally optional and depends on the language and limits of the injured person’s own policy. A UIM claim typically requires proof of the other driver’s fault, the full value of the damages, the limits available from the at-fault driver’s liability insurer, and compliance with the UIM policy’s notice, consent, exhaustion, and settlement conditions.

If you have ever opened a settlement check and realized it would not cover even your hospital bills, you already understand the problem this coverage was built to solve. The sections below explain when a Missouri UIM claim applies, what it requires, how compensation is figured, and where these claims tend to stall.

Last reviewed: June 2026
Reviewed by: Missouri-licensed attorney, Gene S. Hou, Missouri Injury Law Firm.  Editorial note: This article was checked against current Missouri statutes through the Missouri Revisor of Statutes, guidance from the Missouri Department of Commerce and Insurance, and Missouri appellate decisions as of June 2026. It is scheduled for review every six months.

Is Underinsured Motorist Coverage Required in Missouri?

No. Missouri law requires uninsured motorist (UM) coverage on every auto liability policy, but it does not require underinsured motorist coverage. Under RSMo 379.203, each policy issued in the state must include UM coverage for bodily injury of at least $25,000 per person and $50,000 per accident, matching the minimum liability limits set by the Missouri Department of Commerce and Insurance. UIM coverage, by contrast, is purchased separately as an optional add-on, so whether you have it depends entirely on what you elected when you bought your policy.

The distinction matters because the two coverages respond to different facts. UM coverage applies when the at-fault driver had no insurance at all, including many hit-and-run situations. UIM coverage applies when the driver carried liability insurance, but the limits were too low to cover the harm caused. Missouri courts have long treated the underinsured scenario as a separate category; see Cook v. Pedigo, 714 S.W.2d 949 (Mo. App. 1986), which addressed whether an underinsured driver falls within these protections by reference to the financial responsibility standards in RSMo 303.030.

When Can You File a Missouri UIM Claim?

A UIM claim becomes available when the at-fault driver’s liability coverage is not enough to make you whole, and you carry underinsured motorist coverage on your own policy. In practice, several conditions usually line up first:

• The other driver is legally responsible for the crash
• That driver’s liability insurance has limits below the value of your damages
• You hold UIM coverage, and your damages exceed the at-fault policy’s available proceeds

Consider a straightforward example. Suppose your documented losses reach roughly $90,000, and the driver who hit you carried only the $25,000 minimum. The at-fault driver’s liability insurer pays its share, and your UIM coverage may then respond to the remaining amount, up to the UIM limit you purchased. The actual recovery still turns on your policy’s terms and the facts of fault and damages.

Missouri UIM Claim Requirements

A UIM claim is a contract claim against your own auto insurer, so it lives and dies by the policy language and the proof you assemble. The table below outlines what a claimant generally needs to verify.

Requirement	What the claimant should verify
UIM coverage exists	Check the declarations page and any endorsements on your own auto policy
The at-fault driver is legally liable	Preserve the crash report, witness statements, and scene documentation
Damages exceed available liability coverage	Total medical expenses, income loss, future costs, and non-economic harm
Policy conditions are satisfied	Review notice, consent-to-settle, exhaustion, cooperation, and proof-of-loss provisions
Deadlines are met	Check both Missouri law and any enforceable contractual deadline in the policy

Because of the policy controls, two people with similar crashes can have very different outcomes based solely on how their contracts are written. Reading the declarations page early, before you talk numbers with any adjuster, is one of the most useful things you can do.

Steps to File an Underinsured Motorist Claim

The process tends to follow the same order whether your losses are modest or severe. Treat the list below as a working sequence rather than a rigid rule, since real claims rarely behave perfectly.

Step 1: Report the Crash to Your Own Insurer

Notify your auto insurer promptly after the crash, even before you know whether the other driver was adequately insured. Providing early notice protects your rights and satisfies the policy’s reporting requirements. Stick to verifiable facts such as date, location, and the basic sequence of events, and avoid speculating about the extent of your injuries or who was to blame.

Step 2: Document Fault and Damages

Strong documentation is what separates a paid claim from a disputed one. Build a file that an adjuster cannot easily discount.

• The police crash report and any responding officer’s notes
• Photographs of both vehicles, the scene, road conditions, and visible injuries
• Names and contact details for every witness, plus medical records and bills

Step 3: Pursue the At-Fault Driver’s Liability Coverage

Many Missouri UIM policies require the insured to exhaust the at-fault driver’s liability limits before seeking UIM benefits, although the controlling language is the actual policy. That usually means resolving the liability claim first, whether by settlement or judgment. Before you finalize anything, confirm whether your policy contains a consent-to-settle condition, because settling without the required consent can affect your UIM rights.

Step 4: Open and Support the UIM Claim

Once the liability portion is resolved, present the UIM claim to your own insurer in writing. A complete demand generally pairs a clear damages calculation with the records that support it.

• A damages total broken into medical, wage, and non-economic categories
• The supporting records, the liability settlement documentation, and proof that the at-fault limits were used

Step 5: Negotiation, Appraisal, or Arbitration

A first offer may come in below the documented value, and a measure, evidence-based exchange is how most UIM claims reach a fair settlement. If the parties cannot agree, some policies route the dispute to arbitration rather than court. The procedure depends on the policy, so check the dispute-resolution clause before assuming how a disagreement will be decided.

How UIM Compensation Is Calculated

UIM compensation reflects the documented value of your losses, reduced by any amount already recovered and limited by your UIM coverage. Recoverable damages commonly include past and future medical care, lost income and reduced earning capacity, and non-economic harm such as pain and suffering.

Missouri also follows pure comparative fault, which the Missouri Supreme Court adopted in Gustafson v. Benda, 661 S.W.2d 11 (Mo. banc 1983). Under that rule, a claimant’s recovery is reduced by their percentage of responsibility rather than barred outright, so a person found 20 percent at fault on a $100,000 claim may still pursue $80,000. How fault is allocated, and how it interacts with policy offsets, can meaningfully change the final number.

UM vs. UIM Coverage in Missouri

The two coverages are easy to confuse because the names are so similar. The table below sets them side by side.

Feature	Uninsured Motorist (UM)	Underinsured Motorist (UIM)
Triggering situation	The at-fault driver had no liability insurance	The at-fault driver had insurance, but the limits were too low
Required in Missouri?	Yes, on every auto liability policy (RSMo 379.203)	No, generally optional
Availability in Missouri	Mandatory minimum of $25,000 per person and $50,000 per accident	Purchased as an optional add-on, with limits that the policyholder selects
Common trigger	A no-insurance crash or a hit-and-run	Small liability limits set against large damages
Pays from	Your own auto insurer	Your own auto insurer, after the liability proceeds are applied
Main policy issue to review	Whether a hit-and-run qualifies and the notice timing	Exhaustion, setoff, consent-to-settle, and stacking language

Policy Provisions That Can Affect a UIM Claim

Once a UIM claim is opened, the insurer evaluates coverage, causation, damages, exclusions, offsets, and compliance with policy conditions. That review can create a dispute even though the claimant is the insurer’s own policyholder. A few provisions deserve close attention.

Exhaustion Requirements

Many policies require that the at-fault driver’s liability limits be used up before UIM benefits apply. The precise trigger and whether a settlement for less than the limits still satisfies it depend on the wording.

Setoff Provisions

Some policies reduce the available UIM benefit by amounts already paid by the liability insurer. Whether a setoff applies and how it is calculated are determined by the contract language rather than by a single statewide rule.

Consent-to-Settle Clauses

Many policies require the insured to obtain the insurer’s consent before settling with the at-fault driver, partly to protect the insurer’s subrogation rights against that driver. Settling without the required consent can jeopardize the UIM claim, so the safer path is to confirm the condition first.

Bad-Faith and Vexatious Refusal

When an insurer refuses to pay a covered loss without reasonable cause, Missouri law may allow additional damages and attorney’s fees for vexatious refusal to pay under RSMo 375.420. Missouri courts have applied that statute in the uninsured and underinsured context; see Qureshi v. American Family Mutual Insurance Co., 604 S.W.3d 721 (Mo. App. E.D. 2020). Consumers can also file a complaint with the Missouri Department of Commerce and Insurance.

Stacking Underinsured Motorist Coverage in Missouri

Stacking refers to combining coverage across more than one vehicle or more than one policy to increase the total available benefit. Whether UIM coverage can be stacked in Missouri depends on the policy language. The Missouri Supreme Court allowed stacking where the policy’s definitions brought underinsured motorist coverage within its uninsured motorist provisions; see Krombach v. Mayflower Insurance Co., 827 S.W.2d 208 (Mo. 1992). In the uninsured context, anti-stacking clauses have been treated as void against public policy; see Shepherd v. American States Insurance Co., 671 S.W.2d 777 (Mo. banc 1984). Because the results depend on the contract, the declarations page and definitions section should be reviewed before assuming whether stacking is available.

Missouri UIM Claim Deadlines

Two clocks can run at the same time, and missing either one can end a claim. The lawsuit against the at-fault driver for the underlying injury generally must be filed within five years under RSMo 516.120. A UIM claim, however, is a contract claim against your own insurer, and contract claims may be governed by a different statutory period, with many policies also imposing a contractual deadline for demanding UIM benefits or arbitration. Because the contractual deadline can be shorter than the statutory one, it is wise to confirm both early rather than assume the longer period applies.

Frequently Asked Questions

Is underinsured motorist coverage required in Missouri?

No. Missouri requires uninsured motorist coverage on every auto liability policy under RSMo 379.203, but underinsured motorist coverage is optional. You have UIM coverage only if you added it to your policy, so the declarations page is where you confirm it. Many drivers carry the state minimum and never realize the gap until a serious crash exposes it.

How do I know whether I have UIM coverage?

Check your declarations page and any endorsements, where UIM coverage and its limits are listed separately from liability and UM coverage. If the page is unclear, your agent or insurer can confirm the coverage and limits in writing. Keeping a current copy with your records makes the answer quick to find after a crash.

Must I obtain my insurer’s consent before settling with the at-fault driver?

Often, yes. Many Missouri UIM policies include a consent-to-settle condition that protects the insurer’s right to pursue the at-fault driver. Settling the liability claim without the required consent can reduce or void your UIM benefits. The safest approach is to review the clause and notify your insurer before finalizing any settlement.

Can Missouri UIM coverage be stacked?

Sometimes. Whether you can combine UIM coverage across vehicles or policies depends on the policy’s definitions and anti-stacking language. The Missouri Supreme Court permitted stacking in Krombach v. Mayflower Insurance Co., 827 S.W.2d 208 (Mo. 1992), where the contract’s wording allowed it. Reviewing the definitions section is the only reliable way to know.

Does the liability insurer have to pay its full limits first?

Usually, the policy requires it, but the exact trigger varies. Many UIM policies condition benefits on exhausting the at-fault driver’s liability limits, while others accept a settlement for the available amount with the insurer’s consent. The controlling language is your own policy, so the exhaustion clause should be read closely before settling.

What documents are needed for a UIM demand?

A strong demand pairs proof of fault with proof of damages. That generally includes the crash report, photographs, witness information, complete medical records and bills, wage-loss documentation, and the liability settlement paperwork showing the at-fault limits were applied. Organizing these before you submit the demand tends to shorten the review.

Can an insurer reduce UIM benefits by the at-fault driver’s payment?

It can, if the policy contains a setoff provision. Some contracts subtract the liability payment from the UIM limit, while others treat UIM as additional coverage on top of the liability limit. Whether a reduction applies depends on the wording, which is why the setoff and limits language deserves careful review.

What happens when several injured people share one liability limit?

When multiple people are injured in a single crash, a single per-accident liability limit may be divided among them, leaving each person underinsured. In that situation, each claimant may look to their own UIM coverage for the shortfall. The available recovery still depends on each person’s policy limits and the documented value of their losses.

Can a passenger make a UIM claim?

Often, yes. A passenger may have access to UIM coverage under the vehicle’s policy or under a policy where they qualify as an insured, such as a resident relative’s policy. Which coverage applies depends on the policy definitions and the passenger’s relationship to the named insured. Reviewing each potentially applicable policy is the practical first step.

Which policy applies when the injured person was driving a borrowed vehicle?

It depends on the policies involved. Coverage may come from the borrowed vehicle’s policy, the driver’s own policy, or a resident relative’s policy, and the order can be affected by other-owned-vehicle and priority-of-coverage clauses. Because more than one policy can be in play, each should be reviewed to identify available UIM benefits.

Speak With a Missouri Underinsured Motorist Attorney

A shortfall after a serious crash does not have to come out of your own pocket. Missouri Injury Law Firm handles underinsured motorist claims on a no-recovery, no-fee basis, so an initial review costs you nothing.

Call today for a free case review. We will read your policy, calculate the full value of your damages, and identify the exhaustion, setoff, consent, and stacking issues that often decide these claims. You focus on recovery, and we will handle the claim.