In the aftermath of a serious motor vehicle collision, the discovery that the at-fault driver carries no insurance or maintains only minimum liability limits can transform what seemed like a straightforward claim into a complex coverage puzzle. For professionals advising clients who hold multiple automobile insurance policies, whether through personal vehicles, business fleets, or family arrangements, a critical question inevitably arises: can uninsured or underinsured motorist coverage be aggregated across these different policies to provide greater protection? This practice, commonly known as stacking, represents one of the more nuanced and jurisdiction-dependent areas of Canadian motor vehicle insurance law. Understanding when stacking is permitted, when it is prohibited, and how provincial regulatory frameworks shape these outcomes is essential knowledge for insurance professionals, legal practitioners, and risk managers working with clients across the country.
The concept of stacking uninsured motorist coverage emerges from a straightforward premise. When an individual pays premiums on multiple automobile insurance policies, each containing uninsured or underinsured motorist protection, elementary fairness might suggest that all of those coverage limits should be available when a claim arises. If a policyholder maintains two vehicles, each insured with $1 million in underinsured motorist coverage, the intuitive expectation might be that $2 million in total protection exists. However, the reality across Canadian jurisdictions is considerably more complex, shaped by statutory provisions, regulatory requirements, standard form policy language, and decades of judicial interpretation that have created a patchwork of rules varying significantly from province to province.