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Written by:
Prachi Singh
Contributing Writer
Prachi is an insurance writer with a master’s degree in business administration. Through her writing, she hopes to help readers make smart and informed decisions about their finances. She loves to travel and write poetry.
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Reviewed by:
Laura Longero
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Executive Editor
Laura is an award-winning editor with experience in content and communications covering auto insurance and personal finance. She has written for several media outlets, including the USA Today Network. She most recently worked in the public sector for the Nevada Department of Transportation.

Question: What do stacked and non-stacked mean when it comes to car insurance?

Answer: Stacking typically refers to an option you can select for uninsured motorist bodily injury (UM) and/or underinsured motorist bodily injury (UIM) coverages. 

Stacking uninsured motorist coverage and/or underinsured motorist policies is an option that allows you to increase the limits you select for your UM/UIM bodily injury coverage. Limits increase based on the number of cars you are insuring. You will pay a higher car insurance premium for this increased protection level.

Here is an example of stacking:

John has limits of $100,000 per person and $300,000 per accident (written as 100/300) for his uninsured motorist bodily injury coverage and is insuring two vehicles. If he leaves them “unstacked,” or non-stacked as you called it, John’s limits would stay at 100/300. Instead, if John chose to stack his UM coverages, his limits would double to $200,000 per person and $600,000 per accident (200/600).

By selecting stacking for your uninsured/underinsured motorist bodily injury coverage, you increase your limits for each coverage by the number of cars you insure. Generally, there is no limit on the number of vehicles that can be insured and, thus, stacked this way.

The Property Casualty Insurance Association of America (PCIAA) lists nearly 30 states whose statutes, rules, and/or case law either do not address the issue or specifically allow stacking. However, in many states that allow stacking, auto insurers are permitted to include policy language that prevents policyholders from stacking UM/UIM coverage. So, while your state might permit stacking, if your policy explicitly forbids it, you cannot stack your benefits.

Since laws in each state vary widely for UM/UIM stacking, check with your state’s insurance regulator or insurance agent to determine if you can stack your UM/UIM benefits.

Stacking within one policy vs. stacking across policies

When you stack UM and UIM coverages, you have two options: stack within one policy or stack across policies.

Stacking within one policy means you can stack your uninsured and/or underinsured bodily injury coverage when you have more than one car on the same policy. So, if you have four cars on your auto policy, each with UM limits of $100,000, you can choose to stack these and combine the coverage limits for a total limit of $400,000.

Stacking across policies works if you have two or more separate auto policies for your household vehicles. If you have $100,000 per person UM limits on each vehicle and are hit by an uninsured driver, you can file a claim under each car’s policy. Thus, if you have two separate policies in this scenario and your damages come to $150,000, you can make a $100,000 claim under the first car’s UM coverage and then a second claim for the remaining $50,000 under your second car’s UM coverage. 

A reason to stack your coverages is to obtain much higher limits for UM and UIM coverage. However, if you’re pinching pennies, you may want to hold off on stacking since you’ll pay more for the privilege (because your car insurance company could possibly have to payout more if you used your UM/UIM coverage). 

 — Michelle Megna contributed to this story.

Laura Longero

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Laura Longero

Executive Editor

Laura is an award-winning editor with experience in content and communications covering auto insurance and personal finance. She has written for several media outlets, including the USA Today Network. She most recently worked in the public sector for the Nevada Department of Transportation.

John McCormick

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John McCormick

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John is the editorial director for CarInsurance.com, Insurance.com and Insure.com. Before joining QuinStreet, John was a deputy editor at The Wall Street Journal and had been an editor and reporter at a number of other media outlets where he covered insurance, personal finance, and technology.

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Leslie Kasperowicz is an insurance educator and content creation professional with nearly two decades of experience first directly in the insurance industry at Farmers Insurance and then as a writer, researcher, and educator for insurance shoppers writing for sites like ExpertInsuranceReviews.com and InsuranceHotline.com and managing content, now at CarInsurance.com.

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Nupur Gambhir is a content editor and licensed life, health, and disability insurance expert. She has extensive experience bringing brands to life and has built award-nominated campaigns for travel and tech. Her insurance expertise has been featured in Bloomberg News, Forbes Advisor, CNET, Fortune, Slate, Real Simple, Lifehacker, The Financial Gym, and the end-of-life planning service.

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Contributing Writer

Prachi is an insurance writer with a master’s degree in business administration. Through her writing, she hopes to help readers make smart and informed decisions about their finances. She loves to travel and write poetry.