Fairfax County, VA Property Tax Appeal Guide for 2027

Fairfax County property tax appeals for tax year 2027

Fairfax County assesses real estate annually at fair market value, with January 1 as the effective assessment date. For tax year 2027, the valuation date is January 1, 2027. Fairfax County’s 2027-specific forms and deadlines were not published in the reviewed sources as of this analysis on 2026-06-20, so this page uses the county’s recurring rules and the most recent published county instructions for planning.

Key dates

Item	Planning date for 2027	What it means
Target valuation date	January 1, 2027	Evidence should address value and uniformity as of this date.
DTA administrative appeal deadline	April 1, 2027	Fairfax County’s recurring administrative appeal deadline. Electronic or email filings are normally due by 4:30 p.m. Eastern.
Board of Equalization appeal deadline	June 1, 2027	Fairfax County’s recurring BOE deadline. Electronic, upload, email, or drop-off delivery is normally due by 4:30 p.m. Eastern, with postmark rules for mailed BOE appeals.

The most recent Fairfax County appeal page states that administrative appeal applications for the 2026 cycle had to be postmarked by April 1, filed online, or emailed by 4:30 p.m., and that BOE appeals had to be postmarked by midnight on June 1 or dropped off, uploaded, or emailed by 4:30 p.m. (Fairfax County Real Estate Assessment Appeals). Fairfax County’s BOE page also describes June 1 as the BOE filing deadline set by county code, with the next business day applying if the deadline falls on a Saturday, Sunday, or county holiday (Fairfax County BOE).

Official appeal body

Fairfax County’s official appeal body is the Board of Equalization of Real Estate Assessments (BOE). The BOE is an independent body appointed by the Board of Supervisors and has the power to increase, decrease, or keep the same assessment after review (Fairfax County BOE).

Fairfax County also allows a Department of Tax Administration (DTA) administrative appeal. The county says filing with DTA is recommended, but it is not a prerequisite to filing with the BOE (Fairfax County Real Estate Assessment Appeals).

Reasons to appeal

Use the official Fairfax County reason that matches the evidence:

• FAIR MARKET VALUE: Comparable properties or other market evidence indicate a lower fair market value than the assessment as of January 1, 2027.
• LACK OF UNIFORMITY: Similar properties in the same general area or assessment neighborhood are assessed materially differently without supportable differences in characteristics.
• ERRORS IN PROPERTY DESCRIPTION: The county record uses incorrect facts, such as lot size, square footage, condition, flood plain, topography, zoning, or similar property-description data.

Comparable sales and assessment evidence

For a January 1, 2027 assessment, use sales from the prior calendar year, January 1, 2026 through December 31, 2026. Fairfax County’s administrative appeal form asks for 1 to 5 “Uniformity and Sales Comparables” and explains the prior-year sales rule in the 2026 form: 2025 sales apply to the 1/1/2026 assessment, while 2026 sales are not applicable until the 1/1/2027 assessment (2026 Fairfax County administrative appeal application).

Good comparable evidence should involve similar properties in the same general area or Fairfax County assessment neighborhood. Use Fairfax County’s Real Estate Assessment Information Site where available to check sales and assessment-neighborhood information (Fairfax County Real Estate Tax FAQ). Fairfax County did not publish fixed gross-living-area percentage, lot-size percentage, or mileage caps in the reviewed sources. Similarity, physical comparability, and location or assessment-neighborhood relevance control.

Market-value sales should generally be arm’s-length transactions: a willing buyer and seller, unrelated parties, no duress, adequate exposure to the market, and typical financing terms. Bank foreclosure, related-party, distress, or otherwise non-representative sales should usually be excluded or clearly explained.

BOE evidence rules

If you submit an appraisal report or professional opinion to the BOE, it should be complete as originally prepared and signed. Fairfax County says BOE written and supplementary evidence must be submitted with the application by the filing deadline, and that no additional written materials, visual presentations, or documentary evidence other than maps or photographs will be accepted at the hearing (Fairfax County BOE appeal application).

Tax rate context

For estimating possible tax impact, TaxSauce uses the latest adopted countywide base real estate rate found in the reviewed sources: $1.12 per $100 of assessed value, which is 0.0112 as a decimal rate. Additional district rates or service charges may apply depending on the property’s tax district (Fairfax County Real Estate Tax Rates).

A simple estimate is:

assessment change × 0.0112 = estimated annual countywide base tax change

For example, a $25,000 assessment change would equal about $280 using only the countywide base rate. This is an estimate, not a prediction of outcome or final tax bill.

Local volume context

Fairfax County mailed more than 357,000 updated 2024 real estate assessment notices, a useful volume metric for understanding the scale of the county assessment process (Fairfax County News Center).

How TaxSauce can help

TaxSauce can help you organize Fairfax County assessment data, compare similar properties, identify possible FAIR MARKET VALUE, LACK OF UNIFORMITY, or ERRORS IN PROPERTY DESCRIPTION issues, and prepare a filing packet for your review. You choose whether to file, what evidence to include, and how to submit it to Fairfax County.