This map is informational only. It is not legal advice. Rent-cap status here is inferred from public assessor and permit records, not from any official determination. The underlying data is incomplete and sometimes wrong, and several exemptions can't be seen in it at all. Treat this as one source among several. Before acting on anything you see here, confirm it against your lease, your landlord, county records, or a tenant-rights attorney.
Data current as of July 20, 2026. Assessor extracts, Seattle permit records, and the published cap percentage were last pulled on that date. Anything recorded since then won't appear.
Washington's HB 1217 (RCW 59.18.710 through .730) took effect May 7, 2025 and sunsets July 1, 2040. It limits most residential rent increases to the lesser of 10% or 7% plus CPI, no more than once every 12 months, with no increase during a tenancy's first 12 months. The Department of Commerce publishes the figure each July; the current one shows in the legend and on each building's card.
The law exempts several kinds of housing, including new construction, nonprofit and housing-authority ownership, LIHTC developments, and small owner-occupied properties. Only some of those are visible in county data.
| Situation | What the map uses |
|---|---|
| Seattle, permit matched (~700 buildings) | The certificate-of-occupancy date from Seattle SDCI's public certificates-of-occupancy dataset, matched to a "New" construction permit. The building's card links that permit so you can check it yourself. |
| Everywhere else | The assessor's recorded year built, standing in for the certificate-of-occupancy date. It's a year, not a date, so a building sitting right on its 12-year cutoff is genuinely ambiguous. |
| Nonprofit or housing-authority exemption | Whether the county lists the property as tax exempt on the county's parcel record. The map calls a building exempt only if every tax account on the parcel is exempt. That tells you something about who owns the building, not whether it actually qualifies under HB 1217, so it can miss exempt buildings and flag ones that aren't. |
| LIHTC and owner-occupancy exemptions | Nothing. Those facts aren't in King County assessor records at all, so a building that is legally exempt for one of those reasons will still show as covered. |
The 12-year window is evaluated in your browser against today's date, so buildings age into coverage without the map being rebuilt.
This estimates how well a building blocks sound between units, eg. footsteps from above, voices through a shared wall, etc. It says nothing about traffic, aircraft, or any other outside noise. No public dataset measures sound transmission for individual buildings, so this is a rough model built from five assessor fields (construction class, quality grade, condition, year built, unit density). It's an estimate, not a measurement, and no substitute for visiting the building, asking the landlord, or requesting the building plans.
Because it's a model and the reasoning behind it can be wrong for any given building, every card shows the raw assessor record it was built from and a See the numbers breakdown of exactly what each field added or subtracted. If you read that data differently than the model does, trust your own judgement.