Requires health insurers, including private insurers, group health plans, service benefit plans, managed care organizations, pharmacy benefit managers, or other parties that are, by statute, contract, or agreement, legally responsible for payment of a claim for a health care item or service, as a condition of doing business in Washington, to increase their effort to share information with the department and accept the department's timely claims consistent with 42 U.S.C. 1396a(a)(25).

Requires health insurers, as a condition of doing business in Washington, to: (1) Provide, with respect to individuals who are eligible for, or are provided, medical assistance under chapter 74.09 RCW, upon the request of the medical assistance administration, information to determine during what period the individual or their spouses or their dependants may be, or may have been, covered by a health insurer and the nature of coverage that is or was provided by the health insurer, including the name, address, and identifying number of the plan, in a manner prescribed by the medical assistance administration;

(2) Accept the medical assistance administration's right to recovery and the assignment to the medical assistance administration of any right of an individual or other entity to payment from the party for an item or service for which payment has been made under chapter 74.09 RCW;

(3) Respond to any inquiry by the medical assistance administration regarding a claim for payment for any health care item or service that is submitted not later than three years after the date of the provision of such health care item or service;

(4) Agree not to deny a claim submitted by the medical assistance administration on the basis of the date of submission of the claim, the type or format of the claim form, or a failure to present proper documentation at the point-of-sale that is the basis of the claim, if: (a) the claim is submitted by the medical assistance administration within the three-year period beginning on the date the item or service was furnished; and (b) any action by the medical assistance administration to enforce its rights with respect to such claim is commenced within six years of the medical assistance administration's submission of such claim; and

(5) Agree that the prevailing party in any legal action to enforce these provisions receives attorneys' fees as well as related collection fees and costs incurred in the enforcement of these provisions.