Each year in January the County's Department of Real Estate Assessments mails notices of assessment to each property owner in Arlington . These notices state the current year's and prior year's assessments for the property, provide information about deadlines for contesting the assessments, and tell owners how to contact the assessor's office. Assessments are made at 100% of value, meaning there is a direct relationship between the assessed value and the price for which a property would sell. Some states have fractional assessments. Instead of assessing at 100%, a locality might assess at, say, 40% of value. Property owners who receive such fractional assessments must convert them to full value to judge the fairness of the assessments.

In single-family neighborhoods of detached homes or attached dwellings and townhouses, the bases of assessments are the sales of similar properties in those neighborhoods. County appraisers review sales within each neighborhood and, by comparing the sold properties to the unsold properties, develop estimates of typical value for each property in the area. The Department of Real Estate Assessments employs a computer assisted mass appraisal system that generates an estimate of the cost to replace each structure in the neighborhood. The cost estimate is determined from the physical characteristics of the property, such as the number of stories, the size, the number of baths, the quality of construction, the materials used, etc. From the cost to construct, 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. Land values may also be determined, or supported, by estimating the proportionate share of value contributed by the land in improved property sales. For most properties, land is assessed on a per site basis, recognizing that larger or smaller lots do not proportionately increase or decrease from typical market values. Building sites are adjusted in value for variations in size only to the extent that those adjustments are warranted by market evidence.

Residential assessments are based on neighborhood sales occurring from July 1, 2011 through June 30, 2012, with emphasis on 2012 sales. For instance, suppose a property sells for $400,000. The County'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, it is evident 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 develops a range of indicated factors that would adjust the county's estimates of value to the sale prices. From this range of factors, one is selected that represents 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. In some instances, where there are extreme differences in the ranges of indicated adjustment factors, more than one factor may be used for a neighborhood, but the factors are developed by the same techniques and applied to common groups of properties.

For condominium properties the methods of determining assessed value are somewhat different. The county still relies on recent sales as the bases for the assessments, using sales from July 1, 2011 through June 30, 2012, with emphasis on those sales in 2012. Each condominium project is treated as a separate neighborhood. Instead of using a generated replacement cost, the department develops formulas that are uniform for the condominium project. These formulas are based on the descriptive elements of the property and account for such things as living area size, number of baths, floor height, views, parking spaces, etc. These formulas are similar to the replacement cost calculations that are made for other single-family properties in that they produce estimates of value. These estimates of value are compared to the recent sale prices in the condominium to determine appropriate factors to adjust the values to the sale prices. As with other single-family properties, 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.

Late in the year, statistical testing of the market value models developed for single-family neighborhoods and condominium projects is conducted using sales that have occurred after June 30, 2012. These analyses are used to test the predictive accuracy of the assessment models and to identify those that may require refinement.

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. You can access the department's Internet site where you can find the assessment of any property and a list of recent sales in the neighborhood. For those who do not have access to the Internet, the information is available at the department's offices at Courthouse Plaza in Suite 611, 2100 Clarendon Boulevard where assessment personnel are available to assist you with your inquiries from 8:00 a.m. to 5:00 p.m., Monday through Friday. If a visit to the county offices is inconvenient, you may call (703) 228-3920 and ask to speak with the appraiser assigned to your neighborhood; she, or he, will answer your questions and help you to obtain the information you require to judge the fairness of your assessment.