A Simple Idea That Can Double or Triple Your Protection
If you insure more than one vehicle, "stacking" is one of the most valuable — and least understood — options on your policy. It can multiply the uninsured/underinsured motorist protection available after a serious crash. Here's how it works and when it's worth it.
Unstacked: One Vehicle's Limit
With unstacked coverage, a UM/UIM claim is capped at the limit on the single vehicle involved in the crash. If that car carries $50,000 in UM/UIM, $50,000 is the most you can recover — no matter how many other vehicles you insure.
Stacked: Combine Your Limits
With stacked coverage, you add together the UM/UIM limits across all your insured vehicles. Three cars at $50,000 each can provide up to $150,000 of protection for one crash — even if the crash happened in just one of them.
There are two flavors:
- Intra-policy stacking — combining limits across vehicles on one multi-car policy.
- Inter-policy stacking — combining limits across separate policies (for example, household members' own policies).
The Trade-Off
Stacking raises your premium, because it raises the insurer's maximum exposure. But the increase is usually modest relative to the extra protection — and a single serious injury can exhaust an unstacked limit in an instant. For multi-vehicle households, the math often favors stacking.
When Stacking Makes the Most Sense
- You own two or more vehicles
- You carry modest per-vehicle limits and want a higher effective ceiling
- You have family members driving household vehicles
- You want maximum protection against serious injuries
It's Not Available Everywhere
State law controls stacking: some states allow it, some prohibit it, and some require insurers to offer it and let you reject it in writing. The rules — and the premium math — vary, so it's worth reviewing with someone who knows your state.
Find Out What Stacking Would Add
We can tell you whether stacking is available where you live and exactly how much extra protection it would buy for your household. [Check your coverage](/quote) and we'll run the numbers.