Samaritan Ministries, a Christian ministry-based health plan, was ordered to cease operations in Washington on Friday by Insurance Commissioner Mike Kreidler.
The Illinois-based organization's "need-sharing" program is considered insurance under Washington law, he said, despite its unusual structure.
Samaritan Ministries members pay monthly shares of $135 to $320, plus a $170 monthly fee, to cover claims submitted by other members.
The group reviews claims, then publishes the needs for members who pay the medical bills.
Kreidler said Samaritan has not registered with the state, submitted its rates and policies for review, or met solvency requirements.
The organization says it has more than 15,000 members nationwide.
Kreidler spokesman Rich Roesler said the Commissioners Office knows of only one member in Washington.
Samaritan Ministries can appeal Kreidler's order.