Chiropractic insurance billing in Seattle, WA.

Commercial billing in the Seattle-Tacoma-Bellevue market (about 2.8 million commercial enrollees, the state’s largest) is dominated by Premera Blue Cross (the regional Blue Cross plan, with over 50% MSA share) and Regence BlueShield (the Cambia-owned Blue Shield plan), with Kaiser Permanente Washington also significant.

Medicare Advantage penetration in Washington runs near 53% of beneficiaries, just below the 54% national average; notably, Premera exited the Medicare Advantage market effective January 1, 2025, so practices that billed those plans must re-verify patients’ replacement coverage.

King County falls in CMS Medicare locality 02, the distinct “Seattle (King County)” locality, processed by Noridian Healthcare Solutions as the A/B MAC for Jurisdiction F (Part B). It is a separate, higher-cost locality from locality 99 “Rest of Washington”:

Seattle’s practice-expense GPCI (about 1.23, roughly 22% above the national baseline) materially raises non-facility reimbursement versus the rest-of-state PE GPCI of about 1.05, so the metro is a relatively high-GPCI area and codes pay more here than elsewhere in Washington.

Washington is one of only four monopolistic workers’-comp states, so most claims route to the state Department of Labor & Industries (L&I) rather than private carriers, on L&I’s own fee schedule and provider rules. However, the metro’s largest employers self-insure under L&I authority and pay through third-party administrators (Sedgwick, Gallagher Bassett, etc.) – Boeing and aerospace/PACCAR (musculoskeletal and repetitive-strain claims), King County and Costco, plus Amazon warehouse and maritime/port labor – and self-insured employers account for roughly a third of Washington workers’-comp claims, so billers must split work between L&I direct billing and SIE/TPA billing.

When carried, PIP pays eligible auto-injury medical bills first, regardless of fault. Auto-injury cases venue in King County Superior Court, and Washington is an at-fault (tort) state, not no-fault. PIP is optional add-on coverage that insurers must offer and the insured must reject in writing, typically capped at $10,000 in medical for up to three years; where PIP exists it pays the treating provider first regardless of fault, but once it is exhausted bills are commonly carried on a medical lien/letter of protection and collected from the at-fault driver’s liability carrier at third-party settlement, lengthening A/R.

The metro’s dominant health systems – frequent sources of PI referrals and major payer-contract leverage – are UW Medicine (University of Washington), Providence Swedish, Virginia Mason Franciscan Health (CommonSpirit), and MultiCare Health System, alongside Seattle Children’s and Kaiser Permanente Washington.