Washington's rent increase cap for mobile home lots
Under House Bill 1217, a manufactured or mobile home lot in Washington is capped at 5% a year — a flat number in the statute, not the CPI figure the state publishes each July. Here is the rule, the notice deadline, and the exemptions.
The 10% figure is not your number
Every July the Washington Department of Commerce publishes a maximum annual rent increase, and every July it gets quoted at park owners who cannot use it. That figure — 9.683% for 2026, and 10% for 2027, published July 15, 2026 — comes from RCW 59.18.700, which caps ordinary residential tenancies at 7% plus CPI or 10%, whichever is less. Manufactured and mobile home lots are governed by a different chapter entirely, RCW 59.20, and their cap is the flat 5%.
| Manufactured / mobile home lot | Ordinary residential tenancy | |
|---|---|---|
| Statute | RCW 59.20.370 | RCW 59.18.700 |
| Cap | 5% flat | 7% + CPI, or 10%, whichever is less |
| Recalculated each year? | No — fixed in statute | Yes, by Commerce in mid-July |
| 2026 | 5% | 9.683% |
| 2027 | 5% | 10% |
| Notice before increase | Three months (RCW 59.20.090) | 90 days (RCW 59.18.140) |
| First 12 months of tenancy | No increase at all | No increase at all |
The notice timeline for a January 1, 2027 increase
RCW 59.20.090(2) requires written notice three months before the effective date. Read that literally — three calendar months is 92 days across this particular quarter, and a notice counted as "90 days" would be two days short.
| Date | What has to happen |
|---|---|
| October 1, 2026 | The three-month deadline. The notice has to be delivered on or before this date for a January 1, 2027 effective date. |
| January 1, 2027 | The new rent takes effect. |
Use the manufactured-home form. Washington requires specific statutory language in a rent-increase notice, and the Department of Commerce publishes a model form for manufactured-home lots that is not the same as the general residential one. A notice that is right on the number and wrong on the form is still a defective notice.
Run your own number
The exemptions
- Publicly and nonprofit-owned lots. Lots owned by a public housing authority, a public development authority, or a nonprofit, where rents are already regulated by other law or by affordable-housing program requirements — plus qualified low-income housing owned by those organizations. RCW 59.20.380(1).
- The 12 months after a qualifying sale. Following a qualified sale to an eligible organization, rent may rise above the cap in the first 12 months if a majority of the home owners in the community approve it by vote or agreement. RCW 59.20.380(2).
- A home sale in the park. When a rental agreement transfers because a home is sold, the landlord may make a one-time increase not limited by the 5% cap at the first renewal after the transfer — but only if the buyer was given notice of it beforehand. RCW 59.20.380(3).
Note what is not on that list: the 12-year new-construction exemption and the July 1, 2040 sunset both belong to the general residential cap in RCW 59.18.710, not to the manufactured-home cap. We could not find a sunset date on RCW 59.20.370 — read it as permanent until the legislature says otherwise.
Common questions
What is the maximum rent increase for a mobile home lot in Washington?
A flat 5% in any 12-month period. RCW 59.20.370, added by House Bill 1217 in 2025, says a landlord may not increase the rent for a manufactured or mobile home lot during the first 12 months after the tenancy begins, or by more than five percent during any 12-month period of the tenancy. It is a fixed number written into the statute, not a CPI calculation, so there is no annual figure to wait for.
Isn't Washington's rent cap 10% for 2027?
That is the cap for ordinary residential tenancies under RCW 59.18.700 — 7% plus CPI or 10%, whichever is less — which the Department of Commerce recalculates every July. It was 9.683% for 2026 and 10% for 2027. It does not apply to a manufactured or mobile home lot. Applying the 7%-plus-CPI math to a park is the single most common Washington mistake we see, and it produces a number roughly double what the law allows.
How much notice does Washington require for a lot rent increase?
Three months' written notice before the effective date, under RCW 59.20.090(2). Note that the statute says "three months," not "90 days" — those are not the same deadline in most quarters, and the shorter of the two is the one that gets a notice thrown out. Washington also requires specific statutory language, and the Department of Commerce publishes a model form for manufactured-home lots; use it rather than a general residential form.
Can I raise the rent on a new resident who just bought a home in the park?
There is a narrow exception. RCW 59.20.380 allows a one-time increase not limited by the 5% cap at the first lease renewal after a rental agreement transfers because of a home sale — but only if you gave the buyer proper notice of it beforehand. Take the notice requirement seriously: without it, the exception is not available, and the increase is just an over-cap increase.
What else is exempt from the 5% cap?
RCW 59.20.380 exempts lots owned by a public housing authority, a public development authority, or a nonprofit where rents are already regulated by another program, and qualified low-income housing owned by those organizations. There is also a 12-month window after a qualifying sale to an eligible organization during which rent may rise above the cap if a majority of the home owners in the community approve it by vote or agreement.
When do I have to send the notice for a January 1, 2027 increase?
On or before October 1, 2026 — three calendar months before January 1, 2027. Because Washington's park cap is a flat 5% and not an annual figure, there is nothing to wait for: you can prepare and send a Washington park notice in September without checking any publication.
Sources
- RCW 59.20.370 — the 5% manufactured/mobile home lot cap — https://app.leg.wa.gov/RCW/default.aspx?cite=59.20.370
- RCW 59.20.380 — exemptions from the lot rent cap — https://app.leg.wa.gov/RCW/default.aspx?cite=59.20.380
- RCW 59.20.090 — three months’ notice of a lot rent increase — https://app.leg.wa.gov/RCW/default.aspx?cite=59.20.090
- RCW 59.18.700 — the general residential cap (7% + CPI, or 10%) — https://app.leg.wa.gov/RCW/default.aspx?cite=59.18.700
- RCW 59.18.710 — general residential exemptions and the 2040 sunset — https://app.leg.wa.gov/RCW/default.aspx?cite=59.18.710
- HB 1217 (2025) — bill summary and effective date (May 7, 2025) — https://app.leg.wa.gov/billsummary?billnumber=1217&year=2025
- WA Department of Commerce — HB 1217 landlord resource center and annual figures — https://www.commerce.wa.gov/housing-policy/hb1217-landlord-resource-center/
- WA Attorney General — Manufactured/Mobile Home Landlord-Tenant Act — https://www.atg.wa.gov/manufactured-mobile-home-landlord-tenant-act
The other capped state
- Oregon's maximum rent increase for 2027
- The lot rent increase calculator — every state, with the caps applied.
- The rent-increase notice generator — a printable notice with the effective date and notice period filled in.
More Washington reading
- Oregon and Washington rent caps for mobile-home parks — the full plain-English guide, including the penalties for getting it wrong.
- Rent-increase notice generator — draft the letter, then adapt it to the Commerce model form.
- Rent receipt generator — for the payments that come in after the increase lands.
Lot Sidekick keeps each park's rent history, due day, and notice period in one place, so the date of the last increase — the thing the 12-month rule turns on — is never a guess. See how it works or call (425) 405-0734.