Wash. Rev. Code § 25.12.030
The persons forming such partnership shall make and severally subscribe a certificate, in duplicate, and file one of such certificates with the county auditor of the county in which the principal place of business of the partnership is to be. Before being filed, the execution of such certificate shall be acknowledged by each partner subscribing it before some officer authorized to take acknowledgments of deeds; and such certificate shall contain the name assumed by the partnership and under which its business is to be conducted, the names and respective places of residence of all the general and special partners, the amount of capital which each special partner has contributed to the common stock, the general nature of the business to be transacted, and the time when the partnership is to commence, and when it is to terminate.
RCW 25.12.030