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Benton County · Sunnyside, WASunnyside, WA property taxes. Values held. Know when to push back.
The typical home in Sunnyside was worth about $324,000 in January 2026, up 2.3% from a year earlier. In a steady market, an appeal works best for specific homes whose assessment ran ahead of what they'd sell for.
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What Sunnyside home values did
Sunnyside values rose 2.3% in the year to January 2026, reaching a new high. That's stronger than Benton County as a whole (+0.1%).
Values have been roughly flat since January, through August 2026.
| Month | Typical value | vs. a year earlier |
|---|---|---|
| January 2021 | $245,000 | +17.7% |
| January 2022 | $278,000 | +13.1% |
| January 2023 | $290,000 | +4.6% |
| January 2024 | $302,000 | +4.0% |
| January 2025 | $316,000 | +4.7% |
| January 2026 | $324,000 | +2.3% |
| August 2026 (latest) | $321,000 | -0.8% since January |
January 2026 was the highest month since 2021.
What to check on your notice
The typical Sunnyside home gained 2.3% in the year to January 2026. A notice that rose far more than that, or a value above what similar homes nearby actually sold for, is the usual starting point for an appeal.
How Sunnyside compares nearby
Among 6 Benton County places, Sunnyside has the 6th largest drop from its peak and the 6th highest typical value. Statewide, its 1-year change ranks 308th of 372 Washington places, from weakest to strongest.
| Place | January 2026 | 1-year change | vs. peak |
|---|---|---|---|
| Kennewick | $431,000 | -0.2% | -0.3% |
| Richland | $468,000 | +0.4% | At peak |
| Sunnyside | $324,000 | +2.3% | At peak |
| West Richland | $497,000 | -0.1% | -0.4% |
| Prosser | $423,000 | +0.3% | -0.5% |
| Benton City | $429,000 | -1.0% | -1.4% |
Deadline and where to file
Sunnyside values are set by the local county assessor. File your petition with the County Board of Equalization by July 1 of the assessment year, or within 30 days after the assessor mailed your change of value notice, whichever is later. Counties can extend the 30 days to up to 60 days, so check your county.
Reading this in fall 2026? The 2026 deadline has passed (July 1, 2026, or 30 to 60 days after your notice, depending on the county). Your next chance is the 2027 assessment: notices are mailed during 2027 and you can file by July 1, 2027, or 30 days (60 in counties that extended) after your notice date, whichever is later. If you already appealed in 2026, the Board of Tax Appeals deadline is 30 days from the date the county board mailed its decision.
The Benton County guide covers the full Washington appeal process: forms, fees, hearing levels and what happens next.
Building a Sunnyside case
Averages explain why a case might work. The decision turns on evidence about one property. Sunnyside is part of the Kennewick-Richland metro, but your evidence should be local. Sales a few streets away usually beat sales across the metro.
- Send all your evidence with the petition or at least 21 business days before your hearing.
Get your Sunnyside appeal report
Start with your address. Vulorean checks your assessment against recent comparable sales and builds a value report you can bring to your Washington appeal. Eligible reports are free during launch; an account is required and local filing fees are separate.
Check my property and get a report →Vulorean was built for California first. Washington forms, deadlines and filing rules vary, so confirm them with your local office before filing. If something in your report looks wrong, email support@vulorean.com and we'll get it fixed.
Home values: Zillow Home Value Index (ZHVI), all homes, mid-tier, smoothed and seasonally adjusted, through August 2026, from Zillow Research. Rules: RCW 84.40.038, Petition to board of equalization, filing deadlines, Washington DOR Form 64 0075 petition, Washington Board of Tax Appeals FAQs, Washington DOR, how the 1% levy limit works. Vulorean is an independent service, not a government office. Confirm dates and forms with your local office.