We pulled every residential sale the King County Assessor's own eSales database records for the Bellevue-area ZIP codes over the last three years — 2,900+ arm's-length transactions after excluding sales the Assessor flags as non-market. The pattern is consistent: every ZIP has slipped from its 2024–2025 peak, while 2026 assessments are anchored to values as of January 1, 2026. If your assessment notice reflects peak pricing, the Assessor's own sales data may support a lower value.
What the sales data shows, ZIP by ZIP
Median price per square foot, peak quarter vs. the last six months (mid-February through mid-August 2026), plus the median sale price for January–August of 2025 vs. 2026:
| ZIP (area) | Peak $/sqft | Last 6 mo | vs. peak | Median price YoY |
|---|---|---|---|---|
| 98006 (Somerset / Newport / Eastgate) | $910 (2025Q1) | $874 | −4% | $1.96M → $1.77M (−9%) |
| 98005 (Northeast Bellevue) | $1,013 (2024Q3) | $892 | −12% | $2.00M → $2.00M (flat) |
| 98007 (Crossroads / Lake Hills) | $922 (2024Q2) | $838 | −9% | $1.61M → $1.41M (−13%) |
| 98008 (Lake Hills / Robinswood) | $1,064 (2024Q2) | $913 | −14% | $1.65M → $1.50M (−9%) |
| 98040 (Mercer Island) | $1,221 (2025Q1) | $1,162 | −5% | $2.60M → $2.45M (−6%) |
| 98004 (Downtown Bellevue)* | $1,472 (2024Q3) | $1,104 | −25%* | $3.74M → $3.87M (+4%)* |
*98004 is a small luxury segment where the mix of what sells swings hard quarter to quarter — read the direction, not the magnitude.
Zooming into 98006, the most active family ZIP in the set (938 arm's-length sales over three years): median $/sqft peaked at $910 in early 2025 and has drifted down since — July 2026 posted $813/sqft, the lowest month since October 2025. County-wide, the FHFA house price index for the Seattle metro division tells the same story at lower resolution: essentially flat for five straight quarters.
Why this matters for your 2026 assessment
Washington assesses property at 100% of true and fair market value as of January 1 of the assessment year(RCW 84.40.030). To set your 2026 value, the Assessor's mass-appraisal model leans on sales from the months before that date — which, for the Eastside, were the strongest stretch of the market. If prices in your neighborhood have slipped since the data the model was trained on, the gap between assessed value and what comparable homes actually sell for is exactly what a Board of Equalization appeal is designed to correct.
The evidence that wins those appeals is not a Zillow screenshot — it is the same eSales comparable-sales data the Board itself uses, adjusted for size, condition, and sale date. A softening market means the recent, nearby, similar sales you need are on your side.
What to do with this
- Find your assessed valueon your official value notice or the Assessor's parcel viewer.
- Compare it against recent sales of similar homes in your area — not list prices, closed sales. This site builds that comparison for free from official King County data.
- Mind the deadline. A petition must reach the Board of Equalization within 60 days of the date on your value notice (or by July 1 of the assessment year, whichever is later). Value notices mail area by area through the fall — check yours when it arrives. Our step-by-step appeal guide covers the process end to end.
A market that has cooled off its peak is the single most favorable backdrop for an appeal. The data above is free, official, and already organized — the only step left is checking your own number.
Methodology
Source: King County Assessor eSales residential sales records, August 2023 – August 2026, for the ZIP codes shown. Sales carrying an Assessor warning flag (family transfers, partial interests, no market exposure, etc.) are excluded. “Peak” is the highest quarterly median $/sqft in 2024–2026 with at least 15 sales. Medians, not averages, throughout; recent months may still gain a few late-recorded sales.