Wash. Rev. Code § 59.18.270
All moneys paid to the landlord by the tenant as a deposit as security for performance of the tenant's obligations in a lease or rental agreement shall promptly be deposited by the landlord in a trust account, maintained by the landlord for the purpose of holding such security deposits for tenants of the landlord, in a financial institution as defined by *RCW 30.22.041 or licensed escrow agent located in Washington. Unless otherwise agreed in writing, the landlord shall be entitled to receipt of interest paid on such trust account deposits. The landlord shall provide the tenant with a written receipt for the deposit and shall provide written notice of the name and address and location of the depository and any subsequent change thereof. If during a tenancy the status of landlord is transferred to another, any sums in the deposit trust account affected by such transfer shall simultaneously be transferred to an equivalent trust account of the successor landlord, and the successor landlord shall promptly notify the tenant of the transfer and of the name, address, and location of the new depository. If, during the tenancy, the tenant's dwelling unit is foreclosed upon and the tenant's deposit is not transferred to the successor after the foreclosure sale or other transfer of the property from the foreclosed-upon owner to a successor, the foreclosed-upon owner shall promptly refund the full deposit to the tenant immediately after the foreclosure sale or transfer. If the foreclosed-upon owner does not either immediately refund the full deposit to the tenant or transfer the deposit to the successor, the foreclosed-upon owner is liable to the tenant for damages up to two times the amount of the deposit. In any action brought by the tenant to recover the deposit, the prevailing party is entitled to recover the costs of suit or arbitration, including reasonable attorneys' fees. The tenant's claim to any moneys paid under this section shall be prior to that of any creditor of the landlord, including a trustee in bankruptcy or receiver, even if such moneys are commingled.
RCW 59.18.270
*Reviser's note:RCW 30.22.041 was recodified as RCW 30A.22.041 pursuant to 2014 c 37 s 4, effective January 5, 2015.