AppealHarbor Jurisdiction Fairfax County, VA Tax year 2026 Reviewed 2026-08-02

Which comparable sales the county will accept

Last reviewed 2026-08-02, against the county's 2026 appeal forms and the current Virginia Code. The 2027 forms and dates have not been published yet.

An assessment appeal is an argument about what your house was worth on January 1. Almost always, the evidence for that argument is what similar houses actually sold for.

So the sales you pick decide the case. Pick sales the county does not count, and you have handed it a reason to set your evidence aside without ever reaching your argument.

This page covers what Fairfax County treats as a valid sale, which dates qualify, how many sales each route accepts, and why the obvious way to compare two houses gives the wrong answer.

In 30 seconds:

  • The county has a written definition of a valid sale. Foreclosures, family transfers and forced sales are outside it.
  • Sales have to be old enough. A sale after your assessment date supports next year's case, not this year's.
  • The administrative route takes up to five comparable properties. The Board of Equalization takes three.
  • The two forms ask different questions about them. The BOE form asks for each comparable's assessed value, not its sale price.
  • Dividing price by square feet gives a misleading number when the houses are different sizes.
  • Three sales nobody can argue with are worth more than ten that invite argument.

If your tax bill comes from the City of Fairfax or the City of Falls Church, those cities assess separately and set their own rules.

Why sales carry the whole argument

Virginia requires assessments to represent fair market value (what the property would sell for on the open market). The county explains that for most residential properties, fair market value is best determined from comparable sales data, and that its appraisers analyze recently sold properties using computer-assisted mass appraisal.

The county's own definitions page draws a distinction worth holding onto. An assessment is a mass valuation, done once a year, that analyzes large numbers of sales to set values for large groups of similar properties. A single-property valuation is a different exercise entirely.

That is not a criticism of the county. It is what mass valuation is. But it explains where an appeal gets its opening: a process built for groups may not have looked closely at your particular house, and sales are how you show that.

What the county counts as a valid sale

Fairfax publishes its definition. A sale is valid when it is an arm's length transaction conveyed by warranty deed, with all parties knowledgeable of the market, making informed decisions without undue influence, and the property exposed to the open market.

The same page says which transactions are outside that definition: transfers between related parties, duress sales, and foreclosures are not treated as valid sales.

Read that list before you read anything else, because it disqualifies exactly the sales that look most attractive to someone hunting for low numbers. The cheapest recent sale on your street is often cheap for a reason the county has already recorded — and using it invites the county to point that out instead of answering your argument.

Three questions to ask of any sale before you rely on it:

  • Was it on the open market, or did it move quietly between people who knew each other?
  • Was either side under pressure — a divorce, an estate, a foreclosure, a job transfer with a deadline?
  • Was it conveyed by warranty deed?

If you cannot answer, that sale is a liability rather than evidence.

The sale has to be old enough

This trips people, because the rule points backwards rather than forwards.

Your assessment has an effective date of January 1. A sale that closed after that date does not tell anyone what your house was worth on it.

The county forms state it directly. The administrative form puts it in calendar years: sales occurring in 2025 can be considered for the January 1, 2026 assessment, while sales occurring in 2026 are not applicable until the January 1, 2027 assessment. The Board of Equalization form — the BOE is the independent county board that hears assessment appeals — words it as sales finalized on or before the first day of January of the assessment year.

The Code words it a third way. §58.1-3379(C) permits boards of equalization to consider market sales through December 31 of the calendar year before the assessment date.

For nearly every sale, the three agree. They diverge at one edge: a sale closing exactly on January 1 falls inside the BOE form's wording and outside the other two. If your best comparable closed on that date, ask the county how it treats it rather than assuming.

The practical consequence is a scheduling one. A sale that closes in March is evidence for next year. If you find one, note it and calendar it — it does not disappear, it just belongs to a different appeal.

How many sales, and what each form asks

The two county routes want different things, and evidence built for one does not drop unchanged into the other.

Administrative review (DTA) Board of Equalization
Comparable properties accepted Between one and five Three
What the form asks for each Address, map reference, sale date and sale price, comments Tax map reference, owner, address, assessed value (land, building, total), land area, zoning, then free text

That difference in the last row is the one to notice. The BOE form asks what each comparable property is assessed at, not what it sold for. Sale information goes in the free-text box.

There is a logic to it. A uniformity argument is about whether similar properties were treated alike by the same process, and the county's own numbers are the measure of that. But it means a table of sale prices, prepared for the administrative route, does not answer the question the BOE form actually asks.

It also means the work is not interchangeable. If you file administratively in March and go on to the Board in May, the same properties may still be the right ones — but what you have to say about them changes, and the second form is not the first form with a new date on it.

Putting a sale price into a field labelled assessed value is not a formatting slip. It is a factual error on a document you sign.

Why price per square foot misleads

The obvious way to compare two houses is to divide the sale price by the square footage and compare the results. It is also the way that produces wrong answers, and it produces them in a predictable direction.

Here is the problem, generically. Suppose two houses sell in the same neighborhood — one at 2,000 square feet, one at 4,000. The larger one does not sell for twice the price. It sells for more, but not double, because the second two thousand square feet do not add the same value as the first two thousand.

Divide each price by its own square footage and the smaller house shows a higher rate per square foot. Apply that rate to a larger home and you overstate it. Apply the larger home's rate to a smaller one and you understate it.

What the arithmetic actually needs is the additional value that one more square foot adds in that market — not the average across the whole house. Those are different numbers, and only one of them survives contact with someone who does this for a living.

Two related points that follow from the same logic:

Finished basement space is not the same as above-grade space. They do not sell for the same amount per square foot, so adding them together into one number and comparing on that number builds the error in at the start. Notably, the county's own form does not have an above-grade square footage field — it asks for the size of the basement rec room.

The rate has to come from local sales. A figure from a national article, or from another county, describes a different market. How the comparison is built explains where a defensible rate comes from and how it is tested.

Where the sale data is, free

You do not have to buy anything to see sales.

iCare, the county's property search, carries assessed values and physical characteristics for every property, and lets you view residential sales within a property's assessment neighborhood. Sale dates and prices are updated twice weekly.

The residential sales viewer maps valid sales by neighborhood and lets you filter by style, age and size. It is the same neighborhood grouping the county's own appraisers work from, which is a useful thing to be arguing inside of rather than around.

Both are public because Virginia law permits it. §58.1-3122.2 authorises local tax offices to provide internet access to nonconfidential public records.

Three solid sales beat ten shaky ones

There is a reason to be selective rather than thorough, and it is structural.

Your assessment starts out presumed correct. Under §58.1-3379(B) the burden is yours, which means nobody has to disprove your sales — you have to establish them. Every sale you include is something you are asserting, and the Board of Equalization application certifies that the facts in it and attached to it are true, accurate and correct.

So a weak sale does not sit quietly alongside the strong ones. It gives the county something to correct, and a correction changes the subject from your argument to your reliability.

The forms are built for this. Five slots on one route, three on the other. Neither asks for everything you found.

How the three routes compare covers what else each route expects.

Sources