Stacking

Stacking means adding together the uninsured or underinsured motorist limits for more than one vehicle to create a larger total. It applies only to uninsured motorist coverage and underinsured motorist coverage, which protect you and your passengers, not to liability coverage.

There are two kinds. Intra-policy stacking adds the limits for several cars on the same policy; inter-policy stacking adds limits from different policies under which you are an insured, such as your own and a relative's in the same household. Example: you insure three cars, each with $100,000 of UM per person, and an uninsured driver causes you $260,000 in damages. Unstacked, UM pays $100,000. Stacked, up to $300,000 is available, so UM pays the full $260,000 (hypothetical figures).

Whether you can stack depends on your state. According to the Insurance Information Institute, about half the states prohibit it, and some that allow it permit clearly worded anti-stacking clauses. Pennsylvania makes stacking the default and lets a named insured waive it only by signing a statutory form, in exchange for a lower premium; Florida lets insurers offer a cheaper non-stacking option. Stacked coverage costs more, so compare it with simply raising each car's UM limits. Your declarations page shows which you have. See stacked vs unstacked uninsured motorist coverage.