Stacked vs. Unstacked Auto Insurance: What’s Best For You?

When it comes to uninsured and underinsured motorist auto insurance coverage, you have the choice to stack coverage for better protection or stick with unstacked insurance to save money.

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Updated May 13, 2024
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Uninsured and underinsured motorist coverage helps to pay for your expenses if you are ever involved in a car accident with someone who has little to no insurance. If you have stacked auto insurance, it enables you to combine the coverage limits on multiple policies or multiple vehicles to get more coverage in the event you’re injured in an accident with a driver who has inadequate coverage.

Stacked insurance is primarily available with uninsured or underinsured motorist coverage. Some states prohibit or limit stacking insurance coverage, and even if it is allowed in your state, your insurer may not offer it.

Learn more about stacked vs. unstacked auto insurance so you can make the most of your coverage options.

In this article

Stacked vs. unstacked auto insurance

Uninsured and underinsured car insurance coverage is either stacked or unstacked. Stacked coverage combines the coverage limits of multiple policies or vehicles. With unstacked insurance, you would only be covered up to the amount declared on your insurance policy.

Stacked auto insurance Unstacked auto insurance
Coverage Combines coverage limits across multiple policies or vehicles Limited to the coverage limits on the policy insuring the driver and vehicle involved in the accident
Cost Higher premium Lower premium
National availability 32 states (10 only allow horizontal stacking) Everywhere

How does stacked auto insurance work?

Uninsured and underinsured motorist coverage (UM or UIM, respectively) provides bodily injury coverage for medical bills and property damage coverage for repairs or replacement of your vehicle. To use UIM or UM coverage, the underinsured or uninsured driver must be at fault. This coverage also applies if you’re the victim of a hit-and-run accident.

Uninsured motorist coverage helps to cover accidents where the other, at-fault driver has no insurance. Underinsured motorist applies if the other driver doesn’t have enough insurance to cover your medical costs. For example, the other driver might only have state minimum liability coverage with relatively low limits.

However, stacked insurance only applies to the bodily injury coverage on your uninsured and underinsured motorist insurance policy, not the property damage. So you may be able to combine the coverage limits to pay for medical bills but not any repairs or replacement of your vehicle in an accident.

Your coverage can be “stacked” in one of two ways:

  • Vertical stacking: Combines the coverage of two or more vehicles on the same policy. So if you have three cars on a single policy, each with UM/UIM bodily injury coverage of $50,000, you could be covered up to $150,000 by stacking your coverage.
  • Horizontal stacking: Combines the coverage on multiple car insurance policies from the same insurance company within the same household. For example, if you have $50,000 coverage on your UM/UIM policy and your spouse also has $50,000 coverage, you can file claims on both policies for up to $100,000 in total coverage.

Typically, stacked insurance is going to cost more than unstacked insurance because it provides higher insurance limits.

Depending on your state, you may not be able to get stacked insurance, or you may be limited on the kind of stacked insurance coverage you can use. Stacking insurance is allowed in 32 U.S. states, and 10 of those states only allow horizontal stacking of policies.

Here is a list of the states that allow insurance stacking:

Alabama Kentucky New York* Tennessee*
Arkansas Mississippi North Carolina* Texas*
Colorado Missouri Ohio Utah*
Delaware* Montana Oklahoma* Vermont
Florida Nevada Oregon* Virginia
Georgia* New Hampshire Pennsylvania West Virginia
Hawaii New Jersey* Rhode Island Wisconsin
Indiana New Mexico South Carolina Wyoming
*horizontal stacking only

How does unstacked auto insurance work?

Unstacked auto insurance is the standard UM or UIM coverage that you carry on one vehicle. Coverage isn’t combined with other insurance you have on other vehicles. You choose a certain level of coverage and, if you’re in an accident and not at fault, your insurer pays out up to the amount you are covered for.

For example, if you have $50,000 bodily injury UM/UIM coverage, your insurance company will pay up to $50,000 on your medical bills if you are in an accident with someone who is uninsured or underinsured.

Bodily injury claims could include medical expenses, pain and suffering, lost wages, and even funeral expenses, so the costs could be over $50,000, but unstacked insurance will only pay out to the threshold amount.

The benefit of unstacked auto insurance over a stacked policy is a less expensive premium. When you stack policies, you have to pay more for the higher coverage amounts.

What both auto insurance options share

Both stacked and unstacked auto insurance policies are similar in that they offer bodily injury UM or UIM coverage. According to a 2021 study by the Insurance Research Council (IRC), one in eight drivers in the U.S. are uninsured, so having any kind of UM/UIM insurance coverage is important regardless of whether it’s stacked or unstacked.

3 important differences between stacked vs. unstacked auto insurance

The differences between stacked and unstacked auto insurance lie primarily in the coverage amount, the cost, and availability.

1. Coverage

Stacked insurance offers more coverage because it combines the coverage you have on multiple cars or multiple policies. So if you have two cars on one policy, each with $50,000 coverage, stacking insurance on both cars would give you $100,000 coverage. Unstacked insurance would only pay out up to the $50,000 coverage limit on your vehicle.

2. Cost

There are many factors that affect car insurance rates. Unstacked insurance is generally less expensive than stacked insurance because you get less coverage. Although you could save money on car insurance premiums with unstacked insurance, you may be responsible for paying out-of-pocket for accident-related costs above what your insurance will cover.

3. National availability

Unstacked insurance is available anywhere in the U.S. On the other hand, stacked insurance is only offered in 32 states, and 10 of those only allow horizontal stacking where two or more insurance policies are combined. Also, your insurer may not provide stacked insurance even if it is allowed in your state.

Which auto insurance option should you choose?

If you own multiple vehicles or other drivers in your home have car insurance policies, then you may want the added protection that stacking your insurance could provide.

When choosing between stacked or unstacked insurance, you should first check to make sure that stacking is allowed in the state where you live and with the insurance company you use. If not, you really have no choice but to go with an unstacked car insurance policy.

There also may be certain restrictions set in states that allow stacking. For example, in Alabama, you are limited to stacking a maximum of three vehicles on a single insurance policy. So it’s a good idea to check your state laws before getting quotes for a stacked insurance policy.

Since stacked insurance is only available with UM/UIM coverage, you may want to consider the cost of adding the additional coverage to your car insurance if you don’t have it already. While most states require liability car insurance, UM/UIM coverage is only required for drivers in 14 states.


Is stacked or unstacked auto insurance better?

Whether stacked or unstacked auto insurance coverage is better depends on what you consider better. Stacked auto insurance could offer a higher level of coverage, but unstacked insurance is less expensive.

Am I required to have stacked auto insurance?

No, you aren’t required to have stacked auto insurance. You may not live in a state that offers it or have an insurance provider that offers stacked insurance.

Do I get more protection from stacked or unstacked auto insurance?

Stacked auto insurance provides more protection from high medical costs after an accident with an uninsured motorist because it combines the coverage of multiple vehicles or policies.

Bottom line

The cost of medical bills and time lost after an accident could be high, especially if the driver at fault doesn’t have insurance. While uninsured and underinsured motorist insurance could help you cover these expenses, stacking insurance coverage from multiple vehicles or multiple policies could provide extra protection to ensure that your medical bills from the accident get paid.

To find coverage that meets the needs of you and your family, check out our list of the best car insurance companies.

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Author Details

Danielle Letenyei

Danielle Letenyei is a professional writer living in Madison, Wisconsin. Her interests include budgeting, travel, credit cards, insurance, and creative side gigs. She hopes her work on these topics can help others navigate the intricate landscape of personal finance.