Updated September 5, 2026. Quick answer: Washington’s deferral (RCW 84.38, not the newer RCW 84.37, a separate program) is open to homeowners 60 or older or retired due to disability, charges a flat 5% a year, and requires your mortgage holder to cosign the deferral; after which the statute puts that mortgage holder’s interest ahead of the state’s own lien.
What Washington’s deferral requires
RCW 84.38 lets a homeowner 60 or older by December 31 of the filing year, or retired because of disability, defer property taxes and special assessments on their residence. Eligibility is capped at 80% of the claimant’s equity value (RCW 84.38.030), and income is tested against a county-specific threshold set as the greater of the prior year’s threshold or 75% of the county’s median household income (RCW 84.38.020(5)); the Department of Revenue’s current table puts that figure anywhere from $45,450 in the lowest-cost counties to $88,998 in King County for tax years 2024 through 2026, so there is no single statewide dollar number. A separate chapter, RCW 84.37, runs a different deferral with no age test, a flat $57,000 statewide income cap and a floating interest rate; easy to confuse with the senior program, but a distinct statute with different terms.
5% interest, and a lien your own mortgage holder can outrank
Deferred amounts accrue at a flat 5% simple interest a year until paid (RCW 84.38.100), and become a lien in favor of the state. What sets Washington apart is how that lien interacts with an existing mortgage: the statute requires the deferral applicant’s mortgage or purchase-contract holder to cosign the declaration of deferral (RCW 84.38.090), and once that happens, the statute expressly gives the cosigning mortgage holder’s interest priority over the state’s deferred-tax lien. In other words, Washington does not leave lien priority to be fought out later; it is negotiated up front through the cosigning requirement, and the mortgage holder who cosigns keeps the senior position by statute.
When it comes due, and how to apply
The deferred balance becomes payable on sale of the property, on the claimant’s death (unless a qualifying surviving spouse or partner elects to continue it under RCW 84.38.150), on condemnation, when the claimant stops permanently residing on the property, or if any RCW 84.38.030 eligibility condition fails (RCW 84.38.130). Applicants file annually on Department of Revenue Form 64-0011 no later than 30 days before the tax or assessment is due, or 30 days after a delinquency notice, whichever is later (RCW 84.38.040(1)), and the qualifying residence is defined to include up to one acre, extendable to five if local zoning requires it.
Washington’s broader senior property-tax picture, covering exemptions, freezes and circuit-breaker credits, not just the deferral: property tax breaks for seniors in Washington.
How every state’s programme compares: property tax relief for seniors by state. What a deferral means in general, and who it catches out: the property-tax deferral lien trap.
Statutory text read at each state’s own legislature, revisor, or revenue agency this session. General information, not tax or legal advice; rates, caps and thresholds change most years and a county or state agency retains the final say on your own application.