Wash. Rev. Code § 59.18 § 59.18.625

(1) A landlord may not charge or impose any late fees or other charges against any tenant for the nonpayment of rent that became due between March 1, 2020, and six months following the expiration of the eviction moratorium.
(2) For rent that accrued between March 1, 2020, and the six months following the expiration of the eviction moratorium expiration date:
(a) A landlord may not report to a prospective landlord:
(i) A tenant's nonpayment of rent that accrued between March 1, 2020, and the six months following the expiration of the eviction moratorium; or
(ii) An unlawful detainer action pursuant to RCW 59.12.030 (3) that resulted from a tenant's nonpayment of rent between March 1, 2020, and the six months following the expiration of the eviction moratorium.
(b) A prospective landlord may not take an adverse action based on a prospective tenant's nonpayment of rent that occurred between March 1, 2020, and the six months following the expiration of the eviction moratorium.
(3)(a) A landlord or prospective landlord may not deny, discourage application for, or otherwise make unavailable any rental dwelling unit based on a tenant's or prospective tenant's medical history including, but not limited to, the tenant's or prospective tenant's prior or current exposure or infection to the COVID-19 virus.
(b) A landlord or prospective landlord may not inquire about, consider, or require disclosure of a tenant's or prospective tenant's medical records or history, unless such disclosure is necessary to evaluate a reasonable accommodation request or reasonable modification request under RCW 49.60.222 .
(4) A landlord or prospective landlord in violation of this section is liable in a civil action for up to two and one-half times the monthly rent of the real property at issue, as well as court costs and reasonable attorneys' fees. A court must impose this penalty in an amount necessary to deter future violations, payable to the tenant bringing the action.