2856 80th Ave SE, Mercer Island, WA 98040

Office · Mercer Island · Seattle-Bellevue metro, WA

One of 34 reachable office buildings in Mercer Island. Larger than 38% of office buildings in Mercer Island (median 11,827 SF), derived from assessor records.

Usable building area
8,006 SF, King County Assessor
County gross area
12,080 SF, King County Assessor
Excluded area
4,074 SF outside primary usable area
Lot size
6,588 SF, King County Assessor
Year built
2021, King County Assessor
Stories
2, King County Assessor
Predominant use
Office Building, King County Assessor
Assessed value
$2,807,800, per the King County Assessor (not a market appraisal)
Assessed value per usable SF
$350.71/SF, derived from assessor records
Usable area / lot
1.22, derived from assessor records
Vintage
2020s vintage
Zoning
TC, King County
County use code
Office Building

Nearby comparable buildings

Same building type, by distance. Assessor facts only; not an opinion of value.

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Sale history and market context

MakeMe Estimate: $3.81M (estimated market value), with a likely range of $3.36M to $4.4M (half of recent verified sales in this segment landed inside that range). Based on 8 verified arm's-length comparable sales (through 2026-06-01). Not an appraisal. How this estimate works.

lower confidence: 0 comparable sales within 3 miles; nearest 3.3 mi. This property type carries wider measured error; treat the estimate as a starting point. Comparable-sale caveat: the estimate is 33% below the $714.08/SF median of the shown comparable sales.

Comparable sales used as evidence

Recorded arm's-length sales of similar buildings nearby; nearer and more recent sales rank first. Buyer and seller names are withheld. Get this data via API.

Last sold: 2016-07-25 for $1,590,000 (recorded arm's-length sale).

Current ownership dates to 2016 (about 10 years) per recorded transfers.

Source: King County recorded sales extract; buyer and seller shown only when a company or organization. Individual names are withheld.

Value over time

$0$2M$4M$6M201120142017202020232026$1.1MLast sold $1.59M · 2016$3.81M$2.81MCounty assessed valueMakeMe Estimate rangeRecorded sale

Dark line: county assessed value per King County tax rolls. Blue line: our estimate; dashed years are a modeled backcast built from recorded arm's-length sales in the building's segment, not estimates published at the time, and years without enough sales stay unmodeled. The shaded range is the model's measured error band; about half of verified sales in the segment land inside it. Diamonds: recorded arm's-length sales. Not an appraisal. How this estimate works.

Land, site, and value history

Assessed value moved from $675,800 (2011) to $2,807,800 (2026), up 315% over 15 years, per county tax rolls. The 2026 roll splits $2,807,800 into $1,251,700 land and $1,556,100 improvements.

Taxes

Permit history

Source: King County permit records (newest first).