What is the difference between UM and UIM coverage?

Uninsured motorist (UM) covers accidents with drivers who have no insurance at all, including hit-and-runs. Underinsured motorist (UIM) kicks in when the at-fault driver has insurance but their limits aren't enough to cover your losses.

Does uninsured motorist cover property damage too?

It depends on the state. Some states offer uninsured motorist property damage (UMPD), which covers your vehicle's damage from an uninsured driver. Others only offer UM for bodily injury. Check your state's rules.

Can I stack uninsured motorist coverage?

In states that allow stacking, you can combine UM limits across multiple vehicles on your policy. For example, if you have two cars each with $50,000 UM, stacking would give you $100,000 of protection per accident.

How much uninsured motorist coverage should I carry?

A common recommendation is to match your UM/UIM limits to your liability limits. If you carry 100/300 liability, carry 100/300 UM/UIM as well.

Uninsured and Underinsured Motorist Coverage: Why It Matters

June 29, 2026

The uninsured driver problem

An estimated 1 in 8 drivers on U.S. roads has no auto insurance. Many more carry only the state-required minimum — often just enough to cover minor fender-benders, not a serious crash. Uninsured and underinsured motorist (UM/UIM) coverage is what protects you from those drivers.

How UM and UIM coverage work

Uninsured motorist (UM): If a driver with no insurance causes an accident that injures you or damages your vehicle, your UM coverage steps in as though it were the other driver's liability policy. It also covers hit-and-run accidents where the at-fault driver flees.

Underinsured motorist (UIM): If an at-fault driver does have insurance but their limits are too low to pay for all of your losses, UIM makes up the difference — up to your own UIM limit.

Both coverages typically include:

Bodily injury (your medical bills, lost wages, pain and suffering)
In some states, property damage to your vehicle

Which states require it?

About half of U.S. states require UM/UIM coverage as part of a valid auto insurance policy. Others make it optional. See the State Rules section for your state's specific rules.

Even in states where it's optional, declining it is a significant risk given how many drivers are uninsured.

What it costs

UM/UIM coverage is relatively inexpensive, typically adding $50–$150 per year to your premium. Given that a single serious accident with an uninsured driver could leave you with tens of thousands in unpaid medical bills, the cost-benefit ratio strongly favors carrying it.

Frequently Asked Questions

What is the difference between UM and UIM coverage?: Uninsured motorist (UM) covers accidents with drivers who have no insurance at all, including hit-and-runs. Underinsured motorist (UIM) kicks in when the at-fault driver has insurance but their limits aren't enough to cover your losses.
Does uninsured motorist cover property damage too?: It depends on the state. Some states offer uninsured motorist property damage (UMPD), which covers your vehicle's damage from an uninsured driver. Others only offer UM for bodily injury. Check your state's rules.
Can I stack uninsured motorist coverage?: In states that allow stacking, you can combine UM limits across multiple vehicles on your policy. For example, if you have two cars each with $50,000 UM, stacking would give you $100,000 of protection per accident.
How much uninsured motorist coverage should I carry?: A common recommendation is to match your UM/UIM limits to your liability limits. If you carry 100/300 liability, carry 100/300 UM/UIM as well.