Methodology & public records
Where our numbers come from, and what we do with yours.
Everything we say about your property, and every figure on our site and in our letters, comes from records King County publishes for anyone to download. This page explains which records, how each figure is calculated, and what we don’t do.
The records we use
King County publishes its assessment roll as bulk downloads: parcel characteristics, residential building details, recorded sales, the value history for every parcel, and the taxpayer mailing address on file. We also read the Board of Equalization’s published decisions and the county’s levy rates. That is the entire input. We do not buy consumer data, credit information, or anything about you from a data broker, and we do not use information you haven’t already given the county.
How each figure is calculated
| Figure | Value | How |
|---|---|---|
| Residential parcels screened | 511,057 | Every parcel in the county’s residential and condominium files that carries a 2026 assessed value. |
| Owners contacted | fewer than 1 in 500 | Letters mailed this season divided by parcels screened. Recomputed at every mailing; the printed figure is rounded down so it stays true as later letters go out. |
| Recent sales assessed above the price paid | 2,333 of 10,094 | Residential parcels with an arm’s-length sale recorded in 2025 or 2026 (excluding transfers between related parties, foreclosures, and other non-market deeds as flagged by the county), where the 2026 assessed value exceeds the recorded sale price. |
| Median assessment change | −2.3% | Median change from the 2025 to the 2026 assessment (tax years 2026 and 2027 on the county’s roll) across 450,782 residential parcels with both years on record. About 78% went down. |
| Market change | −2.5% | Median residential sale price per square foot for January–June 2026 versus January–June 2025, arm’s-length sales only. |
| Your rank (on your letter) | “top N%” | For a property with a recent sale: its assessed value above the sale price, as a share of the price, ranked among all 10,094 recent sales. For other properties: the gap between the assessed value per square foot and the sales of comparable homes nearby, ranked among all screened parcels. Comparable homes are chosen by distance, size, age, quality grade, condition, lot size, and view, and calibrated against past Board decisions. |
| Tax savings on your letter | estimate | The difference between the assessed value and the recent sale price, multiplied by the levy rate the county applied to your parcel this year. It is arithmetic on the county’s own figures, not a valuation of the property, and the Board decides the actual value. |
What we don’t do
- We don’t state an opinion of your home’s market value. Our letters and this site report what the public record shows. The value asked for in a petition is the owner’s own estimate, adopted after reviewing the evidence.
- We don’t promise an outcome. The Board of Equalization decides, and it can raise an assessment as well as lower it.
- We don’t sell, share, or rent your information. What you send us is used to review and, if you hire us, file your appeal, and for nothing else.
- We don’t keep mailing people who ask us to stop. Email hello@rainierpropertytax.com with “remove” and your address comes off our list.
Filing yourself
You can file your own petition, for free, through the county’s eAppeals site. The deadline is the later of July 1 or 60 days from the mailing date on your value notice. If you’d rather we handle it, our fee is 25% of your first-year tax savings, charged only after the Assessor posts the reduced value.