In Washington the carrier assigns the reviewer — but cannot choose which one

Who assigns the reviewer: carrier-executed, Commissioner-sequenced

The health plan performs the assignment. The Commissioner controls the order. RCW 48.43.535(3) directs the Commissioner to run a rotational registry for assigning a certified IRO to each dispute, and WAC 284-43A-140(2) and WAC 284-43A-150(1) then require carriers to use that registry through the Commissioner's online service and take the next IRO in sequence. A carrier may not assign out of sequence for any reason other than a conflict of interest under WAC 284-43A-050.

That places Washington between two more familiar models: states where the insurance department hand-picks the reviewer, and states where a carrier freely contracts with an IRO of its own choosing. Here the plan does the paperwork and the regulator decides who gets the case.

• 27 IROs are currently certified and selectable in Washington, among them AllMed, KEPRO, MCMC, MAXIMUS Federal Services, Medical Review Institute of America, IPRO, and Advanced Medical Reviews.
• The carrier must assign an IRO within three business days of the enrollee's request.
• It must tell the appellant the assigned IRO's name and contact information within one day of selecting it (WAC 284-43A-140(4)(d)).
• Every assignment is reported to the Commissioner within one business day, and the final IRO decision within three business days of the carrier receiving it.

180 days — and the retrospective denial that skips the grievance

Washington writes the window in days rather than months. The carrier's written internal-review determination has to tell the appellant they have 'up to one hundred eighty days' to request external review, and that the internal decision is final and binding if they don't (WAC 284-43-3150(5)). The rule does not say on its face whether those 180 days run from the date of the final internal determination or from receipt of it, so calendar from the earlier date and don't build a filing plan on the difference. The internal appeal that precedes external review carries its own 180-day clock, and that one expressly runs from the appellant's receipt of the determination (WAC 284-43-3030(4)).

There is no separate, shorter provider clock in Washington. A practice files inside the enrollee's 180 days as the appellant's designated representative (WAC 284-43-3010); a provider seeking expedited review may act as the patient's representative even without a designation already on file.

One category of denial bypasses the grievance process entirely. Where a service carried a valid prior authorization and the carrier denied it retrospectively, the enrollee — or the provider on the enrollee's behalf — may go straight to an IRO, with no obligation to engage in, exhaust, or wait out the carrier's grievance process (RCW 48.43.525(2), as amended by Chapter 157, Laws of 2026; mirrored in RCW 48.43.535(2)).

How to file: the request goes to the carrier, not the regulator

1. 1

   Finish the internal appeal, or claim deemed exhaustion

   Complete the carrier's internal review first. Where the carrier failed to strictly adhere to its own internal-review requirements, WAC 284-43-3130 deems the internal process exhausted and the case can move on.

2. 2

   Send the request to the health plan

   There is no OIC application form or consumer portal for filing. Washington routes the request through the carrier, which then processes the IRO assignment in the Commissioner's online system. Follow the external-review instructions the carrier is required to print in its final internal determination (WAC 284-43-3150(2)).

3. 3

   Wait for the assignment notice

   The carrier assigns an IRO within three business days and must give the appellant the reviewer's name and contact information within one day of selecting it.

4. 4

   Get the evidence to the IRO

   The carrier must deliver its file to the IRO no later than the third business day after receiving the review request, and the enrollee gets at least five business days to send the IRO additional material the reviewer is required to consider (RCW 48.43.535(4)-(5)). In an expedited case that window compresses to 24 hours.

5. 5

   Call OIC if the carrier stalls

   Consumer Advocacy, 800-562-6900. The office does not take the filing — intake is the carrier's job — but a plan that ignores the assignment or notice mechanics is exactly what it is there for.

The clocks, and who pays

• Standard: the IRO must decide within 15 days after receiving the necessary information, or within 20 days after receiving the referral, whichever comes earlier. Where information is incomplete, exceptional circumstances stretch it to no later than 25 days after referral.
• Notice of the result and its basis goes to the enrollee and the carrier within two business days of the determination (WAC 284-43A-070(3)).
• Expedited: 72 hours from receipt of the request, with written confirmation within 48 hours if the request was made orally (RCW 48.43.535(7)(a)). If the ordering provider, contracted or not, determines that standard timing would seriously jeopardize life, health, the ability to regain maximum function, or subject the patient to severe and intolerable pain, the carrier must presume expedited handling (WAC 284-43-3170).
• Upstream, for sequencing: the carrier decides the internal appeal within 14 days, or 20 if the service is experimental or investigational, extendable by 16 more days for good cause (WAC 284-43-3110).
• Cost to the patient and to the practice: none. The carrier pays the IRO's charges (RCW 48.43.535(8)), and carriers must provide the review without imposing any cost on the appellant or their provider (WAC 284-43A-140(4)(b)).
• Washington also caps what the IRO may bill the carrier (WAC 284-43A-130): $600 for contract interpretation, $700 for a standard medical-necessity review, $1,000 for a highly specialized review of a complex condition or an experimental/investigational treatment, and $1,100 where multiple reviewers are used, plus a $200 surcharge for expedited review. Those figures are inclusive of postage, fax, and record handling.
• No dollar threshold. A carrier may not impose a minimum disputed amount as a condition of external review (WAC 284-43A-140(1)), so a small-balance denial is eligible.

Three review rules that cut toward the patient

Washington's rules put unusual weight on the record. If all pertinent information has been disclosed and the reviewers still cannot reach a determination, the IRO must decide in favor of the enrollee. If the carrier refuses to produce available records the IRO requested, the IRO may overturn the denial on that basis alone; the same rule runs the other way when the patient or the provider is the one withholding (WAC 284-43A-070(4)).

The third rule changes how an appeal should be written. Reviewers may override the health plan's own medical-necessity standards where those standards are unreasonable or inconsistent with sound, evidence-based medical practice, and the yardstick is the Washington standard of practice, with national standards usable where there is no evidence that Washington's differs (WAC 284-43A-080, RCW 48.43.535(6)). A determination that overrides the plan has to document why the plan's standard was found unreasonable.

Every Washington IRO decision since 2016 is searchable

The Commissioner publishes a database of individual IRO decisions covering every case since 2016, filterable by year, health insurer, IRO, ICD-10 diagnosis, treatment, reason for appeal, and outcome. The outcome values are Overturned, Partially Overturned, Upheld, Withdrawn by the Carrier, Withdrawn by the Enrollee, and IRO Unavailable. For a practice, that means pulling the actual case narratives for the same payer and the same diagnosis before drafting the appeal.

We do not quote a Washington overturn rate on this page. The database exposes the outcome filter, but we found no OIC publication of an aggregate percentage we could verify against a primary source, and an unsourced number is worth nothing to you. Read the cases instead: how a reviewer described the evidence that carried is more useful to a specific appeal than a statewide average would be.

For Washington providers and billers

Chapter 157, Laws of 2026 — E2SSB 5395, on transparency and accountability in prior-authorization determinations — took effect June 11, 2026, with sections 3 and 7 following on January 1, 2027. Several pieces of it are directly usable when a denial looks thin.

• Every prior-authorization determination notice sent to the enrollee and to the requesting or referring provider must disclose the credentials, board certifications, and specialty of the clinician who had clinical oversight of the determination.
• A medical-necessity determination may be made only by a licensed physician or licensed health professional working within scope, who must actually review the requesting provider's recommendation, the patient's clinical history, and the individual clinical circumstances.
• AI may not be the sole means used to deny, delay, or modify care. Algorithms may process and approve, but a medical-necessity denial requires human review, may not rest on a group data set alone, must be auditable by OIC, and must be periodically reviewed for accuracy.
• A retrospectively denied service that carried a valid prior authorization is deemed approved and payable, and interest accrues on the claim at 1% per month retroactive to the submission date.
• Carriers must post prior-authorization policy changes in a single location on their website, and after December 30, 2030 any new application of prior authorization must be exposed through the electronic PA system.
• By October 1, 2026, carriers report total PA requests, approvals, and denials by health plan and by each delegated benefit manager, including the percentage of denials aided by AI and the percentage of determinations made after the required turnaround times, with OIC publishing annual trend data.