Washington state rent increase cap 2026 HB 1217 sets the residential cap at 9.683% and the manufactured-housing cap at a flat 5% — both per 12-month period, both with a 90-day Department of Commerce notice.

The 9.683% number — derivation and reference period

HB 1217's residential cap formula at RCW 59.18.700(2) is the lesser of (CPI-U Seattle-Tacoma-Bellevue June-to-June + 7 percentage points) and a hard 10% ceiling. The reference period is fixed: BLS CPI-U for the Seattle-Tacoma-Bellevue Metropolitan Statistical Area, 12 months ending the prior June. The Department of Commerce publishes the maximum annual rent-increase percentage each July from the prior June BLS reading. For calendar year 2026 the math is:

• June 2025 CPI-U Seattle: 364.344 (BLS series CUURA423SA0)
• June 2024 CPI-U Seattle: 354.824 (same series)
• 12-month change: (364.344 − 354.824) / 354.824 × 100 = 2.683%
• Plus 7 percentage points: 2.683 + 7.000 = 9.683%
• Versus 10% ceiling: 9.683 < 10 — formula governs.

The 10% ceiling is a hard cap; if the CPI reading + 7 had projected to 11%, the cap would still be 10%. Conversely, the formula has no floor — a deflationary CPI reading could in theory drag the cap to below 7%, though the post-2022 Seattle-MSA inflation trajectory has not produced that outcome. The 7-percentage-point premium over CPI is significantly more landlord-favorable than Oregon's SB 611 cap (7% + CPI-U West Region, lower of formula or 10%) because Seattle's CPI runs structurally higher than the West Region average.

Manufactured/mobile-home parks — flat 5% under RCW 59.20.120

HB 1217 set up two separate rent-cap regimes: residential at RCW 59.18.700 (CPI-formula) and manufactured/mobile-home park spaces at RCW 59.20.120 (flat 5%). The 5% number is not CPI-indexed. It does not move year over year. It applies to every lawful rent increase on a manufactured/mobile-home park space, every 12 months, with a 90-day RCW 59.20.090 notice on the Department of Commerce-prescribed form. The 5% rule also has no expiration — the residential 15-year sunset under RCW 59.18.770 does not apply to manufactured-housing.

The structural difference between the two caps reflects a legislative bargain: residential landlords got a higher headline cap (9.683% in 2026 versus 5%) in exchange for the 15-year sunset; manufactured-housing park operators got a permanent regime in exchange for the lower flat number. Manufactured-housing tenants were the most-displaced cohort in the 2023-24 housing-cost surge and the 5% number reflects that legislative finding.

Who is covered, who is exempt

HB 1217's residential coverage at RCW 59.18.700(3) reaches every residential tenancy subject to the Residential Landlord-Tenant Act (RCW 59.18), with seven exemptions:

1. 12-year first-CoC exemption. Buildings whose first Certificate of Occupancy was issued less than 12 years before the proposed effective date are exempt. The exemption is rolling — a building first occupied January 1, 2015 becomes covered January 1, 2027. This is shorter than Oregon's 15-year first-CoC exemption under ORS §90.323(2)(a) and shorter than Mont. Co.'s 23-year carve-out under §29-53(b)(1).
2. Owner-occupied triplex/fourplex. Owner must reside in the building continuously, and the building must have 3 or 4 rental units total. Continuous residency is a factual question the OAG has taken seriously.
3. Single-family principal residence. Owner-occupied SFR with no more than 2 rental units or bedrooms (including ADU).
4. Shared-bathroom-or-kitchen tenant. Tenant sharing a bathroom or kitchen with the owner. Roommate-style arrangements where the tenant does not have a separate bathroom or kitchen are exempt.
5. LIHTC regulatory-agreement units. WSHFC-regulated LIHTC units operating under a current compliance period are exempt; the regulatory-agreement rent-fixing must be currently in force.
6. Nonprofit affordable housing. Nonprofit-owned affordable housing operating under regulatory agreement.
7. Public-housing-authority units. PHA-owned units operate on their own rent-setting rules and are exempt.

Manufactured-housing coverage at RCW 59.20.020 reaches every manufactured/mobile-home park space subject to the Manufactured Housing Landlord-Tenant Act (RCW 59.20). There is no first-CoC exemption for manufactured-housing — the regime reaches every park space regardless of when the park was first occupied.

If a residential unit fails RCW 59.18.700(3) coverage, no statewide cap governs — but local just-cause-eviction ordinances (Seattle's SMC 22.206.160(C), Tukwila's Renters' Bill of Rights) and local rent-stabilization regimes still apply. Coverage cross-checks for Seattle and Tukwila tenancies should run through both the HB 1217 analysis and the local-ordinance analysis.

The Department of Commerce form and the 90-day rule

HB 1217 requires the rent-increase notice to be on a form prescribed by the Washington State Department of Commerce. Non-conforming notices are void under RCW 59.18.730 — the landlord may not collect any increased rent under a void notice. The form is the only one that lawfully starts a rent-increase clock on a covered tenancy.

The form requires:

• Landlord identification (name, address, contact information).
• Tenant identification (name, unit address).
• Current rent and proposed new rent in dollars.
• Dollar amount of the increase and percentage.
• Effective date — at least 90 calendar days after tenant receipt.
• Statement of HB 1217 compliance: claim of either the residential cap (citing RCW 59.18.700(2) and the Commerce-published cap percentage for the calendar year) or the manufactured-housing cap (citing RCW 59.20.120) or an explicit claim of exemption with statute citation.
• Tenant-rights disclosure (form contains the boilerplate).

The 90-day notice runs from tenant receipt, served per RCW 59.12.040: personal delivery, post-and-mail, or substituted service. Mailed notices add days under the standard substituted-service presumption — practical buffer is 5 business days. Cross-jurisdictional notice-period analysis is at our 30-or-90-day notice deep-dive. The 90-day floor cannot be shortened by lease terms; lease language purporting to allow shorter notice is unenforceable, and the OAG has indicated it considers such clauses prima facie unfair under the Consumer Protection Act.

The first-12-months categorical protection

RCW 59.18.700(1) is the most consequential rule for landlords with new tenancies: a landlord may not increase the rent during the first 12 months after a tenancy begins, regardless of any other coverage analysis. The protection runs from the tenancy start date (not the lease start date), and resets on every legal new tenancy. The first-12-months protection is categorical — a 12-year-CoC exemption does not override it; an owner-occupied triplex exemption does not override it. Even an exempt unit gets the first-12-months protection.

The practical impact: a 12-month lease that ends and renews on a month-to-month basis has its first 12 months of tenancy already counted, and a rent increase can be served immediately at lease expiration with the 90-day clock running into month 13. But a 6-month lease followed by a new 6-month lease is still in its first 12 months of tenancy and cannot take an increase. The 12-month-tenancy clock survives lease-renewals as long as the occupancy is continuous; it resets only on a legal vacancy and a new lawful tenancy starting.

12-month frequency rule and vacancy resets

RCW 59.18.700(4) bars more than one rent increase per unit per 12-month period. The 12 months runs from the effective date of the most recent prior increase. A landlord who served a notice with July 1, 2026 effective date cannot serve another increase taking effect before July 1, 2027 — even if HB 1217 publishes a higher cap in the meantime.

A legal vacancy resets both the 12-month one-increase clock and the first-12-months categorical protection. The new tenancy starts with a market rent (the cap doesn't apply to the new starting rent — only to subsequent increases on the same tenancy) and a fresh 12-month protection window. A "legal vacancy" means:

• Tenant voluntarily moved out.
• Lease expired without renewal.
• Tenant breached the lease for non-payment or material violation.
• Tenant accepted a lawful relocation payment under RCW 59.18.085.

Vacancies caused by retaliatory eviction (RCW 59.18.240) or discrimination (RCW 49.60) do not qualify as legal vacancies; the cap still applies to the next tenancy and the displaced tenant may have additional remedies. The Office of the Attorney General has signalled it considers post-eviction rent resetting in retaliatory-eviction patterns a Consumer Protection Act violation.

What happens if you overshoot or use the wrong form

RCW 59.18.730 stacks four independent remedies on a tenant challenging an unlawful HB 1217 increase:

1. Excess rent collected. The amount the landlord collected above the lawful 12-month-prior-cap-compliant figure, with interest at the Washington statutory judgment rate.
2. Damages of up to three months' unlawful rent. Statutory multiplier modeled on Oregon's three-months-rent penalty under ORS §90.323(7). The "unlawful rent" is the over-cap portion, not the full new rent.
3. Reasonable attorney fees and costs. The attorney-fee hook is what gets tenant-side counsel involved; without it, $7,500 per violation is rarely worth the litigation cost on a single-unit dispute. With the attorney-fee availability, plaintiff's-side firms will take HB 1217 cases on contingency.
4. Civil penalties up to $7,500 per violation. Per-unit, per-notice. A landlord with a portfolio-wide pattern of overcharges faces an aggregate exposure that scales with the unit count.

A non-conforming notice (wrong form, less than 90 days, missing statutory disclosures, no statute citation) 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 voidness rule means a defective notice cannot be cured by partial collection: a landlord who collected the increased rent for 6 months under a void notice owes restitution of the entire 6 months' increase, plus the three-months'-rent multiplier, plus attorney fees, plus civil penalties.

The Office of the Attorney General has parens patriae enforcement authority under RCW 19.86 (the Consumer Protection Act). Tenants may also raise the overcharge or notice defect as a defense in unlawful-detainer proceedings for non-payment of the unlawful portion.

How RentCeiling enforces HB 1217 for you

The free Washington calculator takes (current rent, proposed effective date, building first-CoC date, tenancy start date, residential vs manufactured-housing classification) and returns the 9.683% (or 5%) cap with the 12-year exemption check, the first-12-months protection check, and the 12-month frequency verification. The Washington notice generator emits a printable Department of Commerce-conforming notice with the 90-day RCW 59.18.140 (or RCW 59.20.090) effective-date math, the HB 1217 cap citation, and the right text for both residential and manufactured-housing tenancies. The /compare hub shows how Washington's 9.683% stacks against the nine other jurisdictions modeled here — only Oregon's 9.5% comes close in 2026, and DC's 4.1% standard tier and NYC's 5.25% 2-year RGB rate are far below. Open rule-set at /rules/index.json; the Washington-specific rule-set is at /rules/washington.json.

Run the Washington HB 1217 calculator (free)

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