Uninsured vs. Underinsured Motorist Car Accident Coverage in California: What’s the Difference?

What is Uninsured Motorist Coverage (UM)?

Uninsured motorist coverage steps in when you’re hit by a driver with no insurance at all. It’s an optional add-on to your auto policy, designed to shield you from someone else’s failure to comply with California’s minimum liability law (15/30/5—$15,000 bodily injury per person, $30,000 per accident, $5,000 property damage). UM has two main parts:

• Uninsured Motorist Bodily Injury (UMBI): Covers medical bills, lost wages, and pain and suffering for you and your passengers.
• Uninsured Motorist Property Damage (UMPD): Pays for repairs to your vehicle or other property, with a minimum limit of $3,500 in California.

For example, if an uninsured driver T-bones you on the 101, leaving you with a $20,000 hospital bill and a wrecked car, UMBI could cover your injuries up to your policy limit (say, $50,000), while UMPD handles the car repairs (minus a deductible). You file with your own insurer, who verifies the at-fault driver has no coverage.

What is Underinsured Motorist Coverage (UIM)?

Underinsured motorist coverage, often bundled with UM, kicks in when the at-fault driver has insurance, but their limits are too low to cover your damages. It’s a gap-filler for situations where California’s minimum liability requirements fall short of reality. UIM typically applies only to bodily injury, not property damage, unlike UM.

Picture this: You’re rear-ended on I-5, racking up $25,000 in medical costs. The other driver has the state minimum (15/30/5), so their insurance pays $15,000—leaving you $10,000 short. If your UIM limit is $50,000, it covers that gap, ensuring you’re not stuck with the bill.

Uninsured vs. Underinsured Motorist Coverage in California: What’s the Difference?

 While UM and UIM sound similar, their triggers and scope set them apart:

• Trigger Event: UM applies when the at-fault driver has no insurance. UIM applies when they have some insurance, but not enough.
• Coverage Scope: UM includes both bodily injury (UMBI) and property damage (UMPD). UIM in California typically covers only bodily injury, leaving property damage to your collision coverage or out-of-pocket funds.  You can pay extra to get "full UIM" coverage.
• Claim Process: With UM, your insurer confirms the other driver is uninsured (e.g., via police report or DMV check). With UIM, they calculate the shortfall after the at-fault driver’s insurance pays out its maximum.

 You Need Both UIM & UM Coverage .

California’s 15% uninsured driver rate—among the nation’s highest—makes UM a no-brainer. But UIM is just as critical. The state’s bare-minimum liability (15/30/5) hasn’t kept pace with rising medical and repair costs. A serious injury can easily top $50,000, leaving you exposed even if the other driver is insured. UM protects against the lawbreakers; UIM guards against the legally compliant but underprepared.

We do not know the numbers who have the minimum but a very large number do.  $ 15,000 is the minimum coverage and for any injury involving hospitalization this is a big zero to you.

If you’re budget-conscious, UM alone might suffice—uninsured drivers are a bigger statistical threat. But UIM adds a layer of security for those “in-between” cases, especially in high-cost areas like L.A. or San Francisco. Check your policy: many insurers bundle them, so you might already have both. If not, call your provider (think Allstate, Farmers, or AAA) and tailor your limits to your needs—$15,000 won’t cut it for a major crash.  We believe that there are so many underinsured drivers that not having an UIM policy is a grave mistake.   

 We have had several cases where a person was killed in an accident and both sides had only $ 15,000 in coverage.  In one of those cases the person had a $ 250,000 life insurance policy which helped but in the other we ran an asset search and found nothing we could collect from.  That person seemed out of options.  We were fortunate however that the owner of the car also had insurance.  We were allowed by state law to collect and additional $ 15,000 from the owner as well. 

We recommend getting $ 250,000 or more in both UIM and UM coverage.   

If there is inadequate insurance coverage your recovery options will be limited. Sometimes a low auto policy will not be the end of the financial investigation. Homeowners sometimes have umbrella policies which provide additional coverage and within reason a person's individual assets can be used to satisfy a judgment.

If you have been involved in a serious car, motorcycle or truck accident Daniel Horowitz and his personal injury lawyers will look for the maximum insurance coverage to ensure that you receive proper compensation.