Washington State rent increase calculator HB 1217 (RCW 59.18.700): residential 9.683% in 2026 under min(CPI + 7%, 10%) — manufactured/mobile-home parks flat 5%.

Engrossed House Bill 1217, passed by the Washington State Legislature in the 2025 Regular Session and signed by Governor Bob Ferguson on May 7, 2025, established the first statewide rent-stabilization regime in Washington. It is codified at RCW 59.18.700 — 59.18.770 for residential tenancies and at RCW 59.20.120 — 59.20.125 for manufactured/mobile-home park tenancies. The Washington State Department of Commerce administers the law: it publishes the maximum annual rent-increase percentage each July from the prior June BLS CPI reading, hosts the HB 1217 Landlord Resource Center, and prescribes the statutory notice form. Enforcement is via tenant-initiated civil suits under RCW 59.18.730 — excess-rent damages, up to three months' unlawful rent, reasonable attorney fees, and civil penalties up to $7,500 per violation. The Office of the Attorney General has parens patriae enforcement authority. Most residential provisions sunset July 1, 2040; the manufactured-home 5% cap has no expiration.

For residential tenancies subject to RCW 59.18, the maximum annual rent-increase percentage between January 1, 2026 and December 31, 2026 is 9.683%, calculated from the BLS CPI-U Seattle-Tacoma-Bellevue June 2024 (354.824) to June 2025 (364.344) reading: ((364.344−354.824)/354.824)×100 + 7.000 = 9.683%. For manufactured/mobile-home park tenancies under RCW 59.20, the cap is a flat 5% per 12-month period regardless of CPI. Both caps apply per 12-month period and require at least 90 calendar days written notice on the Department of Commerce-prescribed form. The Department publishes the CY 2027 percentage in July 2026 from the May/June 2026 CPI reading; absent that publication, the statutory ceiling of 10% applies as a conservative assumption.

Probably yes if you own a residential rental property in Washington State subject to the Residential Landlord-Tenant Act (RCW 59.18), regardless of city, AND the building's first certificate of occupancy was issued at least 12 years before the proposed effective date. You are likely exempt if: (a) your building's first certificate of occupancy was issued less than 12 years before the proposed effective date (rolling new-construction exemption); (b) you own an owner-occupied triplex or fourplex and reside in one unit as a principal residence (not corporate ownership); (c) your single-family principal residence rents no more than two units or bedrooms including an ADU; (d) your tenant shares a bathroom or kitchen with you and the property is your principal residence; (e) the property is a LIHTC unit under an enforceable WSHFC regulatory agreement; (f) the property is nonprofit-owned affordable housing under regulatory agreement; (g) the property is a public-housing-authority unit; or (h) the unit is a manufactured/mobile-home park space (covered separately under RCW 59.20 at a 5% cap). Critically: ANY tenancy in its first 12 months is categorically protected from increases regardless of any other coverage analysis. Cities may impose stricter local rules (Seattle Just Cause Ordinance, Tukwila Renters' Bill of Rights); the stricter rule controls.

You must use the rent-increase notice form prescribed by the Washington State Department of Commerce; non-conforming notices are void. The form requires: landlord identification, tenant identification, current rent, proposed new rent, effective date, a statement that the increase complies with HB 1217 (or claim of a specific statutory exemption with citation), reference to the Department of Commerce maximum annual rent-increase percentage for the calendar year of the effective date, and tenant rights information. The notice must be delivered at least 90 calendar days before the effective date, regardless of whether the tenancy is month-to-month or fixed-term. Service must be in the manner prescribed by RCW 59.12.040 — personal delivery, or post-and-mail, or substituted service after good-faith attempts. The form and instructions are at commerce.wa.gov in the HB 1217 Landlord Resource Center.

No. RCW 59.18.700 provides a categorical first-12-months protection: a landlord may not increase the rent during the first 12 months after a tenancy begins, regardless of any other coverage analysis or exemption claim. The protection runs from the tenancy start date — the first day the tenant has the right to occupy the unit under the lease — and resets on every legal new tenancy. After the first 12 months pass, rent may be increased at most once per 12-month period at up to the calendar-year cap (9.683% for 2026 residential; flat 5% for manufactured/mobile-home parks).

The Washington State Department of Commerce takes the 12-month change in the BLS CPI-U series for the Seattle-Tacoma-Bellevue, WA metropolitan statistical area, all items, not seasonally adjusted, measured June to June. It adds 7 percentage points. It takes the lesser of that number and 10%. The resulting figure is the maximum annual rent-increase percentage for the calendar year following publication. The Department publishes the figure shortly after the BLS June CPI release, typically in early July. For calendar year 2026, the published figure is 9.683%. The manufactured/mobile-home park cap is set by separate statute at a flat 5% per 12-month period and is not CPI-indexed.

A legal vacancy lets the landlord reset the rent for the next tenant at market — the cap applies to the next tenancy starting from the new rent, not from the old one. The 12-month one-increase clock AND the first-12-months categorical protection both reset with the new tenancy. A legal vacancy means the tenant voluntarily moved out, the lease expired without renewal, the tenant breached the lease for non-payment or material violation, or the tenant accepted a lawful relocation payment. Vacancies caused by retaliatory eviction (RCW 59.18.240) or discrimination (RCW 49.60) do NOT qualify — the cap still applies and the displaced tenant may have additional remedies.

RCW 59.18.730 makes a landlord who collects rent above the maximum annual rent-increase percentage liable to the tenant for: (a) the excess rent collected, (b) damages of up to three months' unlawful rent, (c) reasonable attorney fees and costs, and (d) civil penalties of up to $7,500 per violation. A non-conforming notice (wrong form, less than 90 days, missing statutory disclosures) is void — the landlord may not collect any increased rent under it and remains subject to penalties for any increase that took effect under it. The Office of the Attorney General has parens patriae enforcement authority. Tenants may also raise the overcharge or notice defect as a defense in unlawful-detainer (eviction) proceedings for non-payment of the unlawful portion.

Most residential provisions of HB 1217 — including the 9.683% (2026) residential cap, the 90-day notice form requirement, and the once-per-12-months rule — sunset on July 1, 2040 (15 years from enactment). The Legislature is expected to revisit the regime before sunset; absent action, the residential cap dissolves on that date. The separate 5% rent cap on manufactured/mobile-home park spaces under RCW 59.20.120 has no expiration date and remains in force indefinitely. Local-government rent-control authority (Seattle Just Cause Ordinance, Tukwila Renters' Bill of Rights, etc.) is unaffected by the HB 1217 sunset.