The term "advanced registered nursing practice" is defined as the performance of the acts of a registered nurse and the performance of an expanded role in providing health care services recognized by the medical and nursing professions. Advanced registered nurse practitioners (ARNPs) are authorized to perform all activities registered nurses perform, perform specialized and advanced levels of nursing, and prescribe legend drugs and certain controlled substances.

An ARNP's scope of practice is defined by the Washington State Board of Nursing and includes:

• examining and diagnosing patients;
• admitting, managing, and discharging patients to and from health care facilities;
• ordering, collecting, performing, and interpreting diagnostic tests;
• managing health care by identifying, developing, implementing, and evaluating a plan of care and treatment for patients;
• prescribing therapies and medical equipment;
• prescribing medications when granted prescriptive authority; and
• referring patients to other health care practitioners, services, or facilities.

In 2024, the title for ARNPs was changed to advanced practice registered nurses (APRNs), but the title change is not in effect until June 30, 2027.

A physician assistant (PA) is a person who is licensed by the Washington Medical Commission to practice medicine under the terms of one or more collaboration agreements. A collaboration agreement is a written agreement that describes the manner in which a PA is supervised by or collaborates with at least one physician, which must be signed by the PA and one or more physicians or the PA's employer. PAs may practice in any area of medicine or surgery as long as the practice is not beyond the scope of expertise and clinical practice of the participating physician or physicians within the department or specialty areas in which the PA practices. The participating physician or the PA's employer and the PA must determine which procedures may be performed and the degree of autonomy under which the procedure is performed. 

For health plans, other than health plans offered to public employees, issued or renewed on or after January 1, 2026, a health carrier may not reimburse a contracted APRN or PA in an amount less than the amount that the health carrier would reimburse for the same service if provided by a contracted physician or osteopathic physician in the same service area when an APRN or PA is providing primary care services or behavioral health care services, including medication management and therapy.

A carrier may not pay a contracted physician more by making nonclaims-based payments to physicians that are not also made available to APRNs or PAs for the same service in the same service area. A health carrier may not reduce the reimbursement amount paid to physicians and osteopathic physicians to comply with this requirement.

The Office of the Insurance Commissioner (OIC) must collect data from on the implementation of this requirement beginning January 1, 2026, from health carriers or from other available sources including the all-payer claims database. By July 1, 2027, the OIC must report to the relevant committees of the Legislature on the number of insurers that have changed their reimbursement policy because of these requirements, the number of APRNs or PAs whose reimbursement increased, the number of physicians whose reimbursement decreased, and the cost to insurers to implement these requirements. These requirements do not apply to APRNs or PAs who are employees of a health maintenance organization.

Service area means the geographic location area or areas where a specific product is issued and rated, accepts members and enrollees, and covers provided services. A service area must be defined by the county or counties included, unless the commissioner permits limitation of a service area by zip code in rule or an applicable payment methodology uses an alternative service area designation.