Mason County property tax appeal 2027: deadline, forms and how to file
To appeal your 2027 Mason County assessment, file with the Mason County Board of Equalization by 1 Jul 2027 (July 1 or within 30 days of the notice mailing date, whichever is later), online at www.masoncountywa.gov or by mail.
Protest deadline1 Jul 2027· 253 days left2026 real property Notices of Value were dated September 11, 2026, with a last day to appeal of October 12, 2026 (Mason revalues in the fall).
Data as of 20 Oct 2026 · Mason County Board of EqualizationCheck your own assessment
Free. We compare the value on your notice with recent sales of similar homes nearby and tell you whether an appeal is worth filing. Have your assessment notice and tax bill handy.
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How to file in Mason County
- Step 1 · by 1 Jul 2027
File the appeal
Online at www.masoncountywa.gov with the account number on your notice, or by mailing Form 64 0075. State the grounds the county recognises.
- Step 2 · before the hearing
Prepare and submit your evidence
The assessor’s value is presumed correct; you need specific market evidence that it is wrong (WAC 458-14-046). “Taxes are too high” or a large percentage increase is not enough. Use comparable sales from the last five years, adjusted to January 1 (sales closest to that date count most), a recent appraisal, photos and repair estimates (WAC 458-14-087). Ask the assessor for the comparable sales it used; it must provide them at least 21 business days before your hearing, and new evidence from either side is due 21 business days before it (WAC 458-14-066).
- Step 3
Meet, then hear
An talk to the assessor with County Assessor comes first; if you decline the offer, the Mason County Board of Equalization hears the case. Most reductions happen at the first step.
Before you file: how to read your notice · evidence that works · informal vs formal hearing · when not to appeal
Forms
| Form | Number | Use | Format |
|---|---|---|---|
| Taxpayer Petition to the County Board of Equalization for Review of Real Property Valuation Determination | 64 0075 | The statewide petition. Give your opinion of value and the market evidence behind it; attach the notice if you file after July 1. | |
| Informal Property Tax Appeal (Board of Tax Appeals) | — | Only if you appeal the county board’s decision to the State Board of Tax Appeals. Attach the board’s order. | |
| Review of Real Property Valuation Determination (Appeal Form) | 64 0075 | County-hosted fillable state DOR petition for real property (2026 assessment year edition) | Fillable PDF |
Appeal levels
| Level | Who hears it | Deadline | Cost |
|---|---|---|---|
| Talk to the assessor | County Assessor | Any time; it does not extend the petition deadline | Free |
| Board of Equalization | Mason County Board of Equalization | July 1, or 30–60 days after the notice, whichever is later | Free |
| Board of Tax Appeals | Washington State Board of Tax Appeals | 30 days after the county board’s decision is mailed | Free |
What evidence the board accepts
The assessor’s value is presumed correct; you need specific market evidence that it is wrong (WAC 458-14-046). “Taxes are too high” or a large percentage increase is not enough. Use comparable sales from the last five years, adjusted to January 1 (sales closest to that date count most), a recent appraisal, photos and repair estimates (WAC 458-14-087). Ask the assessor for the comparable sales it used; it must provide them at least 21 business days before your hearing, and new evidence from either side is due 21 business days before it (WAC 458-14-066).
Mason County questions
When is the Mason County appeal deadline for 2027?
No earlier than July 1, 2027. The rule: July 1 or within 30 days of the notice mailing date, whichever is later If your notice was mailed late in the year, the deadline printed on it controls.
How do I appeal my assessment in Mason County?
File online at masoncountywa.gov, or send petition Form 64 0075 to the Mason County Board of Equalization, Board of Equalization, 411 N 5th Street, Shelton, WA 98584-3466.
What evidence does the board accept?
Market evidence: comparable sales from the last five years adjusted to January 1, a recent appraisal, photos and repair estimates. The assessor’s value is presumed correct, and saying taxes are too high is not grounds for a change.
Can I see the assessor’s comparable sales?
Yes. Ask the assessor; it must give you the sales and valuation data it used at least 21 business days before your hearing (WAC 458-14-066). Your own new evidence is due by the same point.
How do I contact the Mason County Assessor's Office?
Mail: Board of Equalization, 411 N 5th Street, Shelton, WA 98584-3466. Phone: 360-427-9670 ext. 268. Hours and walk-in details: masoncountywa.gov.
What if I disagree with the board’s decision?
Appeal to the State Board of Tax Appeals within 30 days after the board’s decision is mailed. There is no filing fee, and late appeals are dismissed.
Check whether yours is over-assessed
Nearby counties
Kitsap County · Thurston County · Grays Harbor County · Jefferson County · Pierce County · Island County · Pacific County
- Mason County Board of Equalization
- Mason County BOE FAQs
- Mason County BOE Forms
- Mason County Assessor
- RCW 84.40.038 — Petition to the county board of equalization
- RCW 84.40.045 — Notice of change in valuation
- WAC 458-14-066 — Exchange of valuation information
- WAC 458-14-087 — Evidence of value
- RCW 84.08.130 — Appeals to the Board of Tax Appeals
- Washington DOR — Appeal my property assessment
- Board of Tax Appeals — Residential property appeals
- U.S. Census Bureau, county population estimates (2024) and county gazetteer (2024).