Washington’s SB 5847, signed into law as Chapter 175 of the 2026 Laws, takes effect June 11, 2026. The bill converts the Department of Labor and Industries’ (L&I) occupational health treatment guidelines from mandatory compliance standards to advisory clinical references. Attending physicians may now deviate from L&I coverage decisions, treatment guidelines, and policies “when medically appropriate,” codifying the reasoning the Washington Supreme Court adopted in its 2018 Murray decision requiring individualized medical determinations over rigid guideline adherence.
The state fiscal analysis projects the change will add roughly $35 million per year in system-wide claim costs.
Who It Affects
Washington’s approximately 400 self-insured employers, covering roughly 900,000 workers, bear the most direct operational impact. The state’s largest self-insured concentrations sit in aerospace manufacturing, technology, healthcare systems, and public entities including cities, counties, school districts, and the University of Washington system. State-fund employers will feel the cost through premium adjustments over time, but self-insured programs absorb the claims directly.
Three Provisions That Change the Cost Picture
Advisory guidelines. When treatment guidelines shift from binding to advisory, the constraint on per-claim medical intensity loosens. Physicians gain discretion to extend treatment duration, broaden therapy protocols, and prescribe outside the prior formulary boundaries. The result is wider dispersion in per-claim medical costs before the mean itself moves upward.
10-business-day automatic authorization. SB 5847 requires utilization review to be completed within 10 business days of receiving all necessary information. If the clock runs out, treatment is automatically authorized. This compresses the review window that previously served as a cost-management lever. Claims teams that rely on extended utilization review to moderate medical spend lose that friction.
Expanded provider access. Workers may now see nonnetwork providers within a uniform 25-mile radius of their home, replacing the prior tiered system of 15 or 30 miles depending on county population. The bill also classifies coercing a worker toward a specific provider as “unreasonably delaying or refusing to pay benefits,” exposing self-insured employers to good-faith violation penalties ranging from $250 to $2,500 per occurrence.
How It Hits Reserves
The reserve mechanism runs through medical severity and development pattern. Advisory guidelines widen the range of defensible treatment, pushing per-claim medical payments higher in the first 12 to 36 months of maturity. The automatic authorization rule accelerates that spend by removing the utilization review drag that shows up as a slower medical development pattern in historical triangles.
Self-insured employers should expect their medical development factors for post-June 11 accident periods to steepen relative to historical selections. If your actuary’s link ratios rely on Washington experience from the mandatory-guideline era, those factors will understate development going forward. This is the same pattern visible in Hawaii, where HB 1509’s 10-day treatment plan deadline compresses the employer’s review window with a similar deemed-acceptance default.
The broader question is whether to bifurcate the medical development triangle at the June 11 effective date. Blending pre-reform and post-reform experience in a single triangle risks anchoring IBNR to a cost environment that no longer exists.
What This Means for Your Next Review
Before June 11, confirm your TPA’s utilization review workflow can meet the 10-business-day deadline. Flag Washington claims with dates of injury after the effective date so your actuary can isolate the post-reform experience. Ask whether medical severity trend assumptions for Washington need a step adjustment, and whether the historical medical development pattern still applies or should be supplemented with benchmarks from states that already use advisory guidelines.
Beginning December 1, 2026, L&I will report quarterly to the Workers’ Compensation Advisory Committee on claims costs, temporary total disability duration, and related metrics. Those reports will be the first hard data on how advisory guidelines are reshaping medical utilization in practice.