Homeowners are often surprised when a county assessment and a professional appraisal are not the same number. In Washington, both are intended to relate to market value, but they are developed for different purposes, on different timelines, and with very different levels of property-specific analysis.
Is assessed value supposed to be higher or lower than appraised value?
No. There is no rule that one should always be higher. A professional appraisal may be above, below, or close to the county assessed value depending on the effective dates, market changes, property data, condition, renovations, and other factors.
How Washington counties determine assessed value
Washington law requires county assessors to value taxable property at 100% of its true and fair market value. Counties perform annual revaluations using mass-appraisal techniques. Mass appraisal is designed to value large groups of properties efficiently using property records, sales data, statistical models, and common characteristics.
That system is appropriate for property-tax administration, but it does not mean the assessor performs the same property-specific assignment that a fee appraiser completes for an individual client.
How a residential appraisal is different
A residential appraisal is developed for a specific property, client, intended use, and effective date. The appraiser analyzes the subject property and the market evidence relevant to that assignment, including the characteristics that make the home similar to—or different from—competing sales.
Why the two values may differ
- Different effective dates: the assessor’s valuation date and the appraisal’s effective date may not be the same.
- Market movement: prices may have changed between valuation dates.
- Property-record differences: assessor records may not fully reflect remodeling, condition, layout, outbuildings, ADUs, or other characteristics.
- Mass appraisal vs. individual analysis: county models value many properties at once; a fee appraisal focuses on one assignment.
- Unique features: acreage, waterfront, views, condition, unusual design, shops, or other features may require more property-specific analysis.
What if I think my assessment is too high?
Washington property owners may appeal an assessed valuation to the county Board of Equalization. Deadlines and procedures are county-specific, so start by reviewing the notice and contacting the assessor or Board of Equalization. If the dispute turns on the property’s market value as of the applicable valuation date, a property-specific appraisal may provide useful independent evidence.
Learn more about our Property Tax Appeal Appraisal service and our Washington guide to property assessment appeals.
When a private appraisal may make sense
Beyond a tax appeal, owners may need a property-specific opinion of value for an estate, divorce, private sale, family transfer, buyout, or pre-listing decision. If the number will affect a significant financial or legal decision, an independent appraisal can provide a more assignment-specific analysis than a county assessment or automated estimate.
Official Washington reference: Washington Department of Revenue — How residential property is valued.
Need a property-specific valuation? Request an appraisal from Epic Appraisal.
Reviewed by Mark Ellis
Owner | Certified Residential Appraiser, Epic Appraisal
Mark has appraised residential real estate since 2005 and provides valuation services throughout the South Sound and surrounding Western Washington markets. Epic Appraisal resource articles are reviewed for appraisal-industry accuracy and practical relevance.