Washington's 2027 rent cap is 10%: the official number and what it means

How Commerce reached 10%

RCW 59.18.700 uses seven percent plus the June twelve-month change in the Seattle-area CPI-U, or 10%, whichever is less. Commerce lists June 2025 at 364.344 and June 2026 at 380.849. The CPI change is about 4.53%; adding seven percentage points produces about 11.53%.

Because 11.53% is higher than the statutory ceiling, Commerce published 10% as the maximum through December 31, 2027. The cap is a ceiling, not a required increase and not a declaration that every 10% notice is valid.

Use the effective-date year

A landlord planning a January 1, 2027 increase may need to deliver the notice during 2026. The amount calculation should use the rule for the date the new rent becomes effective. The service and notice-form analysis uses the actual law and local rules applicable to the notice process.

RentCap now includes the verified 2027 Washington row, so cross-year calculations do not fall back to an unpublished estimate. The result cites Commerce and records the source-review date.

The five-percent manufactured-home row remains separate

Washington's manufactured/mobile-home lot rent path uses the separate five-percent annual limit in RCW 59.20.370 rather than the Commerce CPI calculation. Identify whether the landlord rents the dwelling unit or the resident owns the home and rents a lot under the manufactured/mobile-home statute.

A property described casually as a mobile home should not automatically be assigned to the lot-rent row. The legal relationship and the notice provisions for that tenancy control.

What does not change just because the number is 10%

The first-twelve-month bar, one-in-twelve-month framework, exemption facts, lease-type parity, required notice form, notice timing, service, and city overlays remain part of the review. Seattle's 180-day housing-cost rule can make the delivery deadline much earlier than the statewide baseline.

A 10% increase can also raise local questions. Seattle EDRA and Portland's unrelated Oregon program have their own rules; Tacoma packet checkout remains paused. Do not treat a round statewide number as a universal safe harbor.

What to record now

Landlords planning 2027 changes should record the current rent, last increase date, tenancy start date, proposed effective date, property type, city, exemption evidence, delivery date, and method. Use the current form and keep the Commerce publication with the calculation file.

Renters who receive a cross-year notice can check the proposed percentage and every non-amount requirement for free. RentCap is not a law firm, and the official publication should be revisited if Commerce corrects its figures or the legislature changes the governing law.

Cross-year planning examples

For a covered $2,000 rent, a 10% 2027 ceiling corresponds to $2,200 before considering timing, prior increases, lease terms, or local rules. For a $1,675 rent, it corresponds to $1,842.50. Rounding upward beyond the ceiling can create an over-cap amount, so preserve the exact calculation and choose a supported payable figure.

A December 2026 effective date still uses the 2026 standard figure of 9.683%, while a January 2027 effective date can use the published 2027 row if the tenancy and notice otherwise qualify. Moving the date across New Year's Day is not a shortcut: the required notice period, rent cycle, first-year boundary, and prior twelve-month increase history still decide whether that date is available.

How RentCap will monitor the published figure over time

Government publications can be corrected. RentCap stores the source URL, publication date, verification date, effective range, formula, and percentage as a dated row rather than a number scattered through templates. Tests compare the calculation and public content with that row, and the changelog makes a later correction visible.

Before serving a high-impact 2027 notice, reopen the Commerce page and confirm that 10% remains the published maximum. A source snapshot in the packet file documents the basis used at the time. If Commerce posts a correction, the application should update the cap table, timeline, guide, sitemap last-modified date, and tests before generating new affected packets.

Oregon follows a different publication schedule and formula, so Washington's 10% must never be copied into Oregon 2027 pages. RentCap will leave the Oregon row and announcement page absent until DAS publishes its official figures. That absence is a deliberate source-control guard, not missing marketing content.