Washington Revised Code Title 18. Businesses and Professions § 18.85.331. License required--Prerequisite to suit for commission

It is unlawful for any person to act as a real estate broker, managing broker, or real estate firm without first obtaining a license therefor, and otherwise complying with the provisions of this chapter.

No suit or action shall be brought for the collection of compensation as a real estate broker, real estate firm, managing broker, or designated broker, without alleging and proving that the plaintiff was a duly licensed real estate broker, managing broker, or real estate firm before the time of offering to perform any real estate transaction or procuring any promise or contract for the payment of compensation for any contemplated real estate transaction.