SeaTac Security Deposit Rules: What the Rental Housing Protections Ordinance Adds to Washington Law

A landlord in SeaTac has to satisfy two sets of rules at once: the Washington statute, Wash. Rev. Code § 59.18.280, and the city's own Rental Housing Protections Ordinance (SMC § 4.05.050). The state law sets the 30-day return deadline after termination of the tenancy and the tenant vacating; the local ordinance adds rules on deposit cap, paying the deposit in installments, receipt and itemization and rent-increase notice. Where the two overlap, the landlord has to meet the stricter one.

What the Rental Housing Protections Ordinance adds

• Deposit cap: The sum of security deposits, non-refundable move-in fees and last month's rent may not exceed one month's rent, except in income-based subsidized housing. (SMC 4.05.050.A.5)
• Paying the deposit in installments: On written request tenants may pay deposits, move-in fees and last month's rent in six equal monthly installments for terms of six months or more, or two installments for shorter or month-to-month terms, with no fee or interest. (SMC 4.05.050.A-C)
• Receipt and itemization: No security deposit may be collected unless the rental agreement is written and a signed, dated condition checklist is given to the tenant. (SMC 4.05.050.E)
• Rent-increase notice: Rent increases over three percent require 120 days' prior notice and increases over 10 percent require 180 days'; subsidized tenancies get 30 days and may terminate early with prorated rent. (SMC 4.05.070.B-C)

Who it covers: Tenancies governed by RCW 59.18 and RCW 59.20 in SeaTac; does not apply where the owner shares the dwelling unit as a primary residence with the tenant (SMC 4.05.020).
Worth knowing: The ordinance does not apply where the owner shares the dwelling as a primary residence with the tenant. Late fees are capped at 2 percent, and a tenant may sue for the greater of double damages or three months' rent. Read from a 2025 archived copy of the city code page.

What Washington law already requires

• Return deadline: 30 days after termination of the tenancy and the tenant vacating.
• Detail: Changed from 21 to 30 days in 2023 (HB 1074). Deductions must be documented with invoices or estimates, and no wear-and-tear deductions are allowed without a signed move-in checklist.
• Itemized deductions: required in writing.
• Forwarding address: not a statutory condition of getting the deposit back.
• Penalty for wrongful withholding: Intentional refusal to return or itemize exposes the landlord to up to twice the deposit plus attorney's fees; missing the deadline forfeits the right to withhold.
• Small claims limit: $10,000.
• Statute: Wash. Rev. Code § 59.18.280.

Using both rules together

1. Read the lease for the deposit amount, the move-in date, and any clause that mentions the ordinance.
2. Check the local rule first: deposit cap under SMC § 4.05.050, then paying the deposit in installments, receipt and itemization and rent-increase notice.
3. Count the Washington deadline of 30 days from termination of the tenancy and the tenant vacating.
4. A written demand that cites both Wash. Rev. Code § 59.18.280 and SMC § 4.05.050 carries more weight than one that cites either alone. Intentional refusal to return or itemize exposes the landlord to up to twice the deposit plus attorney's fees; missing the deadline forfeits the right to withhold.

Frequently Asked Questions

Q: Does SeaTac require interest on security deposits?
A: The Rental Housing Protections Ordinance does not add an interest rule, so Washington law governs. Wash. Rev. Code § 59.18.280 does not require interest on deposits.

Q: Is the SeaTac deposit return deadline different from Washington law?
A: No. The Rental Housing Protections Ordinance does not change the return deadline, so the Washington rule applies: 30 days after termination of the tenancy and the tenant vacating under Wash. Rev. Code § 59.18.280.

Q: Does the Rental Housing Protections Ordinance apply to my unit?
A: Tenancies governed by RCW 59.18 and RCW 59.20 in SeaTac; does not apply where the owner shares the dwelling unit as a primary residence with the tenant (SMC 4.05.020). Check the section cited below for the full list of exemptions before relying on it.

Q: Can I sue my landlord in small claims court for my Washington deposit?
A: Yes. Washington small claims court hears claims up to $10,000, which covers most deposits plus the statutory penalty. A dated written demand that cites Wash. Rev. Code § 59.18.280 is the usual first exhibit.

Sources Checked

• SMC 4.05.050; SMC 4.05.070, Rental Housing Protections Ordinance: code text, read 2026-09-20
• Wash. Rev. Code § 59.18.280 (the Washington statute cited above)
• LeaseLenses Washington deposit data set, last reviewed 2026-09-19; the same data powers the Washington demand letter tool
• Washington landlord-tenant overview and the Washington deposit rules page

This page is general legal information for SeaTac, Washington, not legal advice. Local ordinances are amended more often than state statutes; read the current code text before relying on a figure in court.