Look at your own auto policy first. A Montana auto liability policy must include uninsured motorist (UM) coverage at the state's minimum limits unless the named insured rejected it (MCA § 33-23-201). If the other driver had insurance but not enough, underinsured motorist (UIM) coverage, if you bought it, may pay part of the difference. You may also have a claim against the driver personally, though collecting from someone with no insurance can be hard. This page explains how both coverages work under Montana law. It is part of the Compare section of our Montana Injury Claim Guide.
Uninsured and Underinsured, Side by Side
| Uninsured driver | Underinsured driver | |
|---|---|---|
| The other driver | Had no bodily injury liability insurance or bond at the time of the accident. | Had insurance, but not enough to cover your losses. |
| Coverage that may respond | Uninsured motorist (UM) coverage on your own policy. | Underinsured motorist (UIM) coverage on your own policy, if you bought it. |
| Required in Montana? | Must be included in a Montana auto liability policy unless the named insured rejects it (MCA § 33-23-201). | Not required by the UM statute. It is a separate coverage; check your declarations page. |
| Minimum limits | At least the 61-6-103 limits: $25,000 per person and $50,000 per accident for bodily injury. | Whatever limits you chose. |
| What you must show | That you are legally entitled to recover damages from the uninsured driver: fault and damages. | Fault and damages, plus how your policy's UIM terms apply. |
Uninsured Motorist Coverage in Montana
Montana requires every owner of a registered vehicle operated here to keep liability insurance, and it is unlawful to drive on a public road without it (MCA § 61-6-301). Some drivers do anyway. UM coverage exists for that situation.
Under MCA § 33-23-201, a motor vehicle liability policy for a vehicle registered and principally garaged in Montana may not be issued unless it provides UM coverage, at limits for bodily injury or death at least equal to those in MCA § 61-6-103 ($25,000 for one person and $50,000 for two or more in one accident). The coverage protects people insured under the policy who are legally entitled to recover damages from the owner or operator of an uninsured vehicle because of bodily injury, sickness, disease, or death caused by an accident.
The named insured has the right to reject UM coverage. If you rejected it, the same insurer does not have to include it on a renewal unless you request it in writing. The only way to know is to look at your declarations page, the summary sheet that lists your coverages and limits, or ask your insurer.
Underinsured Motorist Coverage
A serious injury can cost more than a minimum policy pays. When the at-fault driver had insurance but not enough, UM does not apply, because the vehicle was insured. That is what UIM coverage is for. Montana law treats underinsured motorist coverage, like medical payment coverage, as one of the additional coverages a motor vehicle liability policy may include (MCA § 33-23-204), and the UM statute does not require it.
How UIM pays depends on your policy: how it defines an underinsured vehicle, how it accounts for what the at-fault driver's insurer pays, and what its limits are. Read those sections, or bring the policy to someone who can read it with you.
Adding Coverage Together
People with more than one vehicle often ask whether they can add the UM or UIM limits from each vehicle together, which is often called stacking. Montana answers it by statute, subject to what your policy says. Unless the policy specifically provides otherwise, MCA § 33-23-203 says the limits available for one accident are the limits for the vehicle involved; if the vehicle involved is not insured under a policy, they are the highest limits for one vehicle under one policy; and limits under policies from the same company may not be added together if the premiums actuarially reflect that limit and the rates have been filed with the insurance commissioner.
The same statute requires an insurer that charges a premium for a coverage to clearly tell the insured in writing the limits for that premium and whether coverage from one policy or vehicle may be added to another. If you are not sure, ask your insurer for that notice.
Making the Claim
A UM or UIM claim is made to your own insurer, but it is still a claim you have to prove. The statute speaks of insureds who are "legally entitled to recover damages" from the uninsured driver, so you need evidence that the other driver was at fault and of what your injuries cost you. Your own share of fault reduces the recovery (MCA § 27-1-702). Report the crash promptly, follow the notice terms in your policy, keep every medical record and bill, and be as careful with what you say to your own adjuster as with the other side's.
If your insurer delays or underpays a UM or UIM claim without good reason, our insurance claims page explains what Montana law expects of insurers. Our article on being hurt by a drunk driver covers a common version of this problem, and what Montana's minimum car insurance covers explains the limits the other driver may be carrying.
Is This a Claim to Handle Yourself?
Sometimes. A small UM claim for a minor injury that has fully healed can be straightforward. A claim where your losses are larger than the available limits, where more than one policy may apply, or where the insurer disputes fault is harder, because the answer depends on policy language and the statutes above. Our page on whether you need a lawyer for an injury claim goes through when help is worth it and when it is not.
This page explains Montana law in general as of the 2025 Montana Code Annotated. It is not legal advice about your situation, and your policy's own terms control much of how these coverages work.