Single-Family Homes & Condos

Each January, the County’s Department of Real Estate Assessments mails notices of assessment to each property owner in Arlington, which state:

  • the current year’s and prior year’s assessments for the property,
  • information about deadlines for contesting the assessments,
  • how to contact the assessor’s office.

Assessments are made annually and at 100% of fair market value, so there is a direct relationship between the assessed value and the price for which a property would sell.

Single Family Homes

Land Value + Improvement = Total Value

  • County appraisers review sales within each neighborhood and compare similar sold properties to similar unsold properties to develop estimates of typical value for each property in the area.
  • A computer-assisted mass appraisal system generates an estimate of the cost to replace each structure in the neighborhood.
  • Deductions are made to account for the age and condition of the structure.
  • The replacement cost is added to the land value for an indicated total property value.

Land values are determined from:

  • sales of vacant parcels or improved property sales that were purchased for land value and/or
  • estimating the proportionate share of value contributed by the land in improved property sales

For most properties, land value is assessed on a per-homesite basis which attributes a base rate value to the homesite itself, recognizing that larger or smaller lots do not proportionately increase or decrease from typical market values.

Improvement values are determined by:

(Replacement cost new – less depreciation) x market factor

Replacement cost new – Depreciation (calculated by cost approach):

  • Cost to replace a similar house (material cost + labor)
  •  CAMA (computer assisted mass appraisal) system is used to calculate the cost and labor in our region.  It is updated regularly to ensure that the changes in material costs and labor are up to date.

Depreciation (age/effective age/condition/quality):

  • Homes depreciate each year based on the effective age.  Older homes depreciate at a higher rate than newer homes (as updates are made to the costing tables periodically, changes to the improvement value may differ from home to home in the same neighborhood as a result).
  • As improvements are made, effective age, condition and/or quality may increase based on the type(s) of improvements added.

Market factor (market trends indicated by sales comparison approach):

  • Market factor, in percentage, is determined by analyzing 1 year of open market sales that occur in a neighborhood area.
  • Sales date of 1 year and 4 months preceding the year of the assessment are utilized to determine the market trend.  For instance, 2020’s assessment was determined by utilizing sales dated from 9/1/2018 thru 8/31/2019.  This is because from 9/1/2019 thru 12/31/2019, appraisers are analyzing data of over 60,000 parcels that are present in Arlington County.
  • As a part in determining the market factor, sales comparison approach is used.  First, the appraiser visits each property sold to ensure that the County’s assessment record is correct which includes but not limited to size, quality, age/effective age and other features.  The sale price of a property is then compared to the assessment value to determine the market trend.

For example:

  • If a property sells for $400,000. Arlington’s estimate of land value is $200,000, its estimate of building value is $160,000, and the resultant total value is $360,000.
  • Comparing $360,000 to $400,000 shows that the level of estimated value is 90% of the sale price (360,000 / 400,000 = 90%). If the building value is factored by 1.25, the estimated value equals the sale price.

Building cost $160,000
Adjusting factor x 1.25
Adjusted building value $200,000
+ Land Value $200,000
= Total Value $400,000


  • By examining each sale in a neighborhood, the appraiser determines a common or average factor that is applied to all buildings in the neighborhood.
  • For each property in the neighborhood, assessments are calculated by adding the land value and the adjusted replacement cost of the building.
  • More than one factor may be used for a neighborhood where there are extreme differences in the housing stock, but the factors are applied to common groups of properties.


  • As with single family homes, County appraisers rely on recent sales as the bases for the assessments, using sales from September 1st through August 31st, of each year leading up to a January 1st assessment.
  • Each condominium project is treated as a separate neighborhood. Instead of using a generated replacement cost, formulas account for living area size, number of baths, floor height, views, parking spaces, etc. within the condominium project to estimate value.
  • These estimates of value are compared to the recent sale prices in the condominium project to determine appropriate factors to adjust the values to the sale prices.  Common factors are applied to all properties in the condominium to determine the assessed values.
  • A portion of the assessed value is allocated to the building component and a portion is allocated to the land component, as required by Virginia Law.

Whether a traditional detached house, a townhouse, or a condominium unit, ultimately, an assessment should reflect market value and be equitable with comparable properties. The best way to judge the assessment of your property is to compare it to recent sales and to compare it to the assessments of surrounding properties. Since all real estate assessments are a matter of public record, it is a fairly easy task.

Find property assessments & list of recent sales

Online: Property Data Search site

In person: The Real Estate Assessments Office is CLOSED for in-person customer service.

Call: 703-228-3920 to speak with the appraiser assigned to your neighborhood