STATE LAW – WASHINGTON LIBRARY – GUIDE 06
Washington Stacking & Multiple Insurance Policies
Washington stacking analysis asks whether more than one independently applicable coverage may respond to the same loss. The answer depends on the coverage involved, the policies, insured status, other-insurance clauses, and current Washington law.
- Identify every potentially applicable policy and limit.
- Determine whether each policy independently covers the claimant and occurrence.
- Review anti-stacking, other-insurance and anti-duplication language.
- Apply current Washington statutory and appellate authority to the specific coverage.
UIM policy limits may restrict combining coverage
For underinsured motorist coverage, RCW 48.22.030(5) permits a policy to set one accident limit despite the number of covered people, claims, vehicles or premiums. Subsection (6) also permits a policy to cap the total available under other similar insurance at the highest applicable coverage limit.
These provisions authorize policy terms; they do not establish that every policy contains an enforceable restriction. Obtain each policy and endorsement, confirm that the claimant is covered, and read the actual limits and other-insurance language. This statutory UIM framework does not decide every liability, PIP or other coverage question.
Statutory source checked October 22, 2026; policy application and case-specific interpretation require separate review.
Official Sources
Verify current Washington law at the source
The reviewed Washington guide content above is preserved. Use current statutes, insurance regulation, controlling cases and the operative policy before legal reliance.
Sources supporting this guide
Sources checked October 22, 2026. Statutory UIM limits only; liability, PIP and case-specific interpretation remain outside this source check.
Citizen crossroads