[WA] What notice and rent increase limits apply when raising rent at the end of a lease for an ADU in Seattle?

Lexi, Chatbot

I understand that you're dealing with a lease situation, which can be quite complex. Can you tell me if you are the landlord or the tenant in this lease agreement?

Lexi, Chatbot

Have there been any specific issues or concerns that have arisen regarding this lease that you would like to address?

Jon

Hello, and thank you for reaching out! I’m Jon, a licensed attorney with over 13 years of experience, here to help.

Jon

I understand legal matters can feel overwhelming, but you’re in good hands. My goal is to explain things clearly and guide you toward the best possible solution for your situation.

Jon

Just a quick note: our conversation is for general legal information only and does not create an attorney-client relationship.

Jon

Can you please let me know which state (and city, if possible) your property is located in?

Jon

Thank you. Has your current lease agreement with the tenant specified any terms regarding rent increases or notice periods for renewal or changes at the end of the lease?

Jon

Got it, thanks. In Seattle, there are specific regulations around rent increases. Have you checked if there are any local ordinances or state laws that might limit how much you can increase the rent or require a certain notice period? For your specific property, that is.

Jon

In Seattle, rent increases and lease renewals are tightly regulated by a mix of city ordinances and Washington state law, and those rules apply even when the unit is an ADU that serves as the tenant’s primary residence. With a lease ending on February 28, 2027, there are a few key legal requirements you need to be aware of, and the timing matters.

If you plan to raise the rent or any other housing-related charges, Seattle law requires you to give the tenant at least 180 days’ written notice before the increase takes effect. That means if the higher rent would start on March 1, 2027, the tenant must actually receive the written notice no later than September 2, 2026. It is not enough to send it by that date; it has to be received. (Seattle Housing Cost Increases)

Seattle also requires that the notice include specific language explaining the tenant’s rights and providing contact information for the “Renting in Seattle” helpline. If that required language is missing, the rent increase notice can be deemed unenforceable, even if the timing is otherwise correct.

On top of the notice requirement, there are limits on how much you can increase the rent. Washington enacted a statewide rent cap under HB 1217, which applies to most residential tenancies. For rent increases taking effect in 2026, the cap is 9.683%. The official cap for 2027 will be announced in July 2026 and is calculated as 7% plus CPI, but it is generally capped at a maximum of 10% per year.

There is an exemption in HB 1217 for certain owner-occupied properties, most commonly duplexes where the owner lives in one of the units. Whether a detached ADU on a single-family lot qualifies for that exemption is a legally nuanced question and not always clear-cut, so it is something that often warrants careful review before relying on it.

Separately, Seattle’s Economic Displacement Relocation Assistance (EDRA) ordinance can come into play if the rent is increased by 10% or more within a 12-month period. If that happens and the tenant’s household income is below 80% of the Area Median Income, and the tenant chooses to move because of the increase, you may be required to pay relocation assistance equal to three months’ rent. This obligation exists even if the rent increase itself is otherwise lawful.

As for the lease itself, Seattle’s Just Cause Eviction Ordinance means you cannot simply allow a lease to expire and require the tenant to leave without a legally recognized reason. You are required to offer the tenant a reasonable lease renewal.

That renewal offer must be made between 60 and 90 days before the current lease ends, which for a February 28, 2027 expiration means sometime between December 1 and December 31, 2026. Once the renewal is offered, the tenant must be given at least 30 days to review and decide whether to sign it.

Jon

You’re welcome!