New Construction Supplements

In accordance with Virginia Code, 58.1-3292.1 Arlington County creates Supplemental tax assessments for new construction. When certain renovations, additions, or new construction has occurred at a property, new value is typically added to the dwelling. A supplemental tax assessment is the difference between the new assessment and the January 1st value. Arlington County’s real estate appraisers will visit properties where permits have been applied for, and actively monitor the progress of construction. A County appraiser will determine when the new construction is substantially complete. The property will be determined to be substantially complete regardless of occupancy, date of completion, or fitness. When the department determines that the new construction is substantially complete, it will re-assess the parcel in order to include the improvements made to the property.

Original Assessed Value
Land                                      $700,000
Improvement (building) +  $150,000
Total Assessment               $850,000
An addition was completed August 20th = 5 Months Proration (Sept., Oct., Nov., Dec.)
Addition/renovation or new construction adds $200,000 of value to the building

New Assessed Value
Land                                      $700,000
Improvement (building)  + $350,000
Total assessment                $1,050,000
New Assessed Value          $1,050,000
Original Assessed Value  – $850,000
Increase in Value                $200,000

$200,000 ÷ 12 (months) x 5 (months prorated) = $66,666 (Supplemental Assessment)

The Treasurer will apply the tax rate to the supplemental assessment and send out a supplemental bill in January of the following year in addition to the year’s original tax bill.

A notice of supplemental assessment, stating the changes in the assessed value of the parcel, will be mailed to the homeowner on record at the time the notice is mailed out. Supplemental assessment notices are usually mailed out a couple weeks after the appraiser visited the property and verified the substantially complete status. If you have purchased a newly constructed home and the supplemental tax assessment was created before the purchase, who and how the supplemental tax assessment will be paid should be discussed with the builder or title company.
The new assessed value only covers the months post the completion and are in addition to the original assessment for that year. The supplemental assessment information is forwarded to the Arlington County’s treasurer’s office. The Treasurer is in charge of collecting supplemental bill taxes, any questions regarding due dates or payments should be forwarded to the Treasurer of Arlington County.

How to Appeal Your Supplemental Assessment

Owners who receive a supplemental assessment may request a review of the updated value within 30 days of the date on the notice. The review application form should be completed and mailed or emailed to the Department of Real Estate Assessments. All support documentation must be submitted with the review application. After receiving the review request, an appraiser will contact the owner and may request an inspection of the property. A determination will be mailed to the owner within a couple weeks of the review request and any subsequent inspections.

For more information about the supplemental process:

Please contact the assessment office to speak with an appraiser at 703-228-3920 or email with questions at