Start with the assessment year, then save the date of each copy you compare. The Fairfax County Real Estate Assessment site says assessed values are as of January 1 for the year shown, while property characteristics and ownership information update twice weekly. Record any date actually printed for the detail and the day you accessed it. A difference between a saved value and a later display shows that something changed between your two copies; the date of the individual field change needs its own record.
Fairfax’s January 1 date applies to the assessed value only
Keep the value’s January 1 basis attached to the value alone. The county includes sale dates and prices in its update description, and its twice-weekly cadence describes how often data refreshes rather than when a particular field was edited. The date you open or save a page tells you when you saw it.
The assessment landing page documents routes by address, tax map reference number and map. Use the route that matches the identifier you already have, when it is available, and retain the resulting source label.
Keep a small date trail for the comparison
Before comparing a saved record with a current display, write down:
- Assessment basis: the year attached to the assessed value, with January 1 of that year as the county’s stated basis.
- Detail evidence: the exact characteristic, ownership or sale entry you are comparing, plus any date the particular record actually supplies. If none is shown, write “field date not shown” instead of the site footer or your access date.
- Capture: where each copy came from and the date you obtained it. Keep the saved page or document if you have one.
For example, a fictional saved assessment for one year and a later screen showing a different descriptive detail establish a difference between two captures. The day of a physical change, county edit, sale or correction is a separate fact. If the detail matters, the missing evidence is a dated earlier record or a dated correction record, if one exists and can be obtained.
Follow-ups for a Fairfax data mismatch, a missing copy and a search problem
If the current display appears factually wrong, the assessment site directs comments and requests to its Contact Us form; the page also lists 703-FAIRFAX. The Department of Tax Administration’s real estate line is 703-222-8234. Identify the field, property reference, displayed text and evidence of the suspected error. The County decides whether a correction is made.
If the current page is reachable but you need an older version or correction correspondence, name the specific existing record and period you seek. Fairfax County’s FOIA guidance advises identifying the agency that may hold the record and contacting that agency first. The page describes Virginia FOIA as covering Virginia citizens and representatives of the media; the Countywide FOIA Officer is at 703-324-7052. Ask whether historical snapshots or change logs exist; access has stated qualifications and exemptions.
If the page is down, retry the official route later; the site posts a notice when the system is down for maintenance. If the identifier points to a different parcel or address, settle that identity question before comparing values or details. The Fairfax address-change guide addresses a current-versus-historic address, while the PIN history guide explains why a tracking key and a legal boundary are different questions.
How the January 1 date moves through the year
The assessment date also sets a calendar you can use to date a saved copy. For 2026, the County began mailing assessment notices on February 17. Both 2026 appeal windows have closed: the appeals page set April 1, 2026 for an administrative appeal to the Department of Tax Administration and June 1, 2026 for the Board of Equalization. The first 2026 tax installment was due July 28. The second installment is normally due December 5; because that falls on a Saturday in 2026, the County’s Tax Facts and Deadlines page moves it to Monday, December 7, 2026.
For the 2027 assessment year, the same page lists the standing calendar: change notices mailed at the end of February, an April 1 deadline for a DTA appeal, a June 1 deadline for the Board of Equalization, and installments due July 28 and December 5. A date that lands on a weekend or County holiday moves to the next business day. Check the appeals page for the posted 2027 deadlines before you file.
So a printed notice from February describes January 1 values, while a screen saved in August may already reflect an appeal decision or later characteristic edits. If your comparison crosses one of those dates, ask whether an appeal or correction record exists for that year before reading the difference as a change to the property.
What two dated Fairfax assessment copies can show
An assessment display records values and descriptive data; construction dates, ownership transfers and permit, inspection or occupancy approvals come from their own records. If no dated earlier copy is available, describe the comparison as unresolved. Send the exact field and dates with your question to the likely records custodian.
Sources: Fairfax County Real Estate Assessment site, DTA assessment-appeals and Tax Facts and Deadlines pages, 2026 assessment-notice release and Countywide FOIA page, checked October 20, 2026.