Seattle, Washington
King County commercial property tax appeals
Appeals start with the King County Department of Assessments and go to the King County Board of Equalization. Here is how commercial evidence is built, filed and heard in King County.
- Assessor
- King County Department of Assessments
- First-level board
- King County Board of Equalization
- Filing deadline
- Petition postmarked, hand delivered or filed online by the later of July 1 of the assessment year or 60 days after the mailing date printed on the value notice (King County's adopted limit under RCW 84.40.038)
- Commercial assessment level
- 100% of true and fair value
- Value standard
- True and fair value in money (RCW 84.40.030)
- Valuation date
- January 1 of the assessment year, for taxes payable the following calendar year
- Assessment cycle
- Annual revaluation of every parcel to market value, with a physical inspection of each property at least once every six years (RCW 84.41.041)
- Notices mailed
- Change of value notices are mailed area by area through the assessment year; commercial specialty areas (office, retail, industrial, apartments, hotels) generally receive notices in the spring and summer
How King County assesses commercial property
King County revalues every parcel each year at 100% of true and fair value as of January 1, and taxes based on that value are paid the following year. The Department of Assessments mails change of value notices area by area, and commercial property is valued by specialty appraisal teams that publish annual area reports with the rents, vacancy, expenses and cap rates their income models use. Those reports are the first document a consultant should read for any office, retail, industrial or apartment parcel here.
The appeal goes to the King County Board of Equalization, an independent board that hears petitions filed by the later of July 1 or 60 days after the notice mailing date. Petitions are filed through the eAppeal system or on paper, one per parcel, and must state specific reasons. Evidence is exchanged at least 21 business days before the hearing, and hearings run by telephone or as an administrative review on the written record. The Assessor's value is presumed correct, so the petitioner carries a clear, cogent and convincing burden.
The Board issues an order within 45 days after the hearing. Either party can appeal it to the Washington State Board of Tax Appeals within 30 days. For a packet, the strongest King County cases tie a normalized operating statement and leasing evidence to the Assessor's own published parameters for the property's class.
Major commercial submarkets
- Seattle CBD and South Lake Union office
- Bellevue CBD and the Eastside
- Kent Valley industrial
- SoDo and Georgetown industrial
- Redmond and Kirkland tech campuses
- Capitol Hill and Ballard multifamily
Uniformity authority
Wash. Const. art. VII, §1 (taxes uniform upon the same class of property)
Appeal statute
RCW 84.40.038 (petition and deadline); RCW 84.48.010 (county board of equalization); WAC 458-14 (board practice rules)
After the board
Washington State Board of Tax Appeals, filed within 30 days of the mailing date of the Board of Equalization's order (RCW 84.08.130); either the owner or the Assessor may appeal. A formal BTA decision can then be reviewed in superior court
Official forms ATALI ELECTRIC fills for King County
| Form | Filed with | Purpose |
|---|---|---|
| Real Property Petition to the King County Board of Equalization | King County Board of Equalization | Appeals the Assessor's value for one parcel. Every relevant question must be answered with the specific reasons the value is wrong; a petition that only says the value or the tax is too high is rejected under WAC 458-14-056. |
| Agent authorization signed by the owner | King County Board of Equalization | Authorizes a consultant or attorney to file and appear for the owner; file it with the petition so the Board can accept the agent's filing and send notices to the agent. |
| Washington State Board of Tax Appeals Notice of Appeal | Washington State Board of Tax Appeals | Appeals the county board's order within 30 days of its mailing date, choosing a formal or informal hearing. |
Filing system: King County eAppeal online petition system, or the paper Real Property Petition filed by mail or in person in duplicate
Hearings and evidence
Hearings are held by telephone before the Board, or the petitioner can choose an administrative review in which the Board decides on the written record. Scheduling commonly takes six months or more. After evidence and the Assessor's response are exchanged, a petitioner can ask for an expedited hearing. The Board issues a written order to both parties within 45 days after the hearing.
- 01WAC 458-14-066: both the petitioner and the Assessor must provide valuation evidence at least 21 business days, excluding legal holidays, before the hearing; the postmark controls. If the other side objects to late evidence the Board may exclude it, postpone, or hold the record open.
- 02WAC 458-14-056: a petition is complete only if every relevant question is answered with reasons specific enough to inform the Board and the Assessor; incomplete petitions are rejected by notice.
- 03RCW 84.40.0301: the Assessor's value is presumed correct, and the petitioner must overcome it by clear, cogent and convincing evidence.
- 04The Board does not consider percentage increases, the amount of tax, personal hardship, or comparisons of other properties' assessments as evidence of market value.
- 05File a separate petition for each parcel, in duplicate if filing on paper.
Income evidence
The Department of Assessments values most commercial property with income models built for each specialty area and publishes annual area reports showing the market rents, vacancy, expense and capitalization rates applied by property type and class. That makes the income case in King County a direct argument with the Assessor's published parameters: show that the subject's market rent, vacancy, or cap rate falls outside the range used for its class, supported by leasing data and sales near January 1. Actual operating statements carry weight when they track the market, and the clear, cogent and convincing standard means a single rent figure without support rarely moves the Board.
Practitioner notes
- Values are as of January 1 but taxes are paid the following year, so a 2026 appeal affects the 2027 tax bill. Track both years when estimating savings.
- Notices arrive by area at different times through the year, so the 60-day window is different for each parcel in a multi-building portfolio. Calendar every notice date.
- Downtown Seattle office has seen deep vacancy since 2020, and the Assessor's office models use class-specific vacancy and rent. Class B and C buildings often have the strongest argument when they are modeled close to Class A assumptions.
- Either side can appeal the county order to the Board of Tax Appeals, so a large reduction may be contested by the Assessor at the state level.
King County appeal questions
Last verified October 2026 against the assessor, board and statute.
What is the King County appeal deadline?
The later of July 1 of the assessment year or 60 days after the mailing date printed on the value notice. Petitions must be postmarked, hand delivered or filed online by that date.
When does a 2026 reduction affect the tax bill?
Values are set as of January 1, 2026 for taxes payable in 2027. If the Board's decision comes after the bill is issued, the Treasurer issues a revised statement or a refund.
Can I appear in person?
Hearings are held by telephone, or the petitioner can choose an administrative review in which the Board decides on the written evidence without participation.
What burden does the owner carry?
The Assessor's value is presumed correct, and the petitioner must show it is wrong by clear, cogent and convincing evidence under RCW 84.40.0301.
Nearby jurisdictions
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