The Big Stretch

The District caps increases in property taxes on primary residences at 10 percent a year. Maryland caps the increase in taxable assessments at 10 percent -- even less in some local jurisdictions. Virginia has no cap.

The actual amount residents pay is determined each year by elected officials, who set the rate at which the assessed properties are taxed. The rates are set after public hearings.

In the meantime, homeowners who believe their properties were overvalued can appeal. Typically, only a small portion of property owners appeal -- from 1 to 6 percent depending on the jurisdiction, according to several area assessors. Of those who appeal, a third succeed in getting their assessment changed.

Because of the mass-review nature of assessments, tax officials readily acknowledge that some may be inaccurate. Each jurisdiction has a review and appeal process, as well as a deadline, some of which are fast approaching.

Assessors encourage homeowners to carefully go over the information about their houses. Data that is used to determine the assessment may be wrong or outdated -- for example, the condition of a basement or the number of fireplaces.

Thomas Rice, the director of Arlington County's Department of Real Estate Assessments, recalled a time years ago when he reviewed a property with records indicating it had two bathrooms. The owner said there was only one. What Rice discovered upon entering the house was a toilet fixture plopped in the middle of a 1,000-square-foot basement.

"It was recorded as if it were a finished bathroom with walls and doors and tiles," Rice said, guessing that the property owner had intended to construct a bathroom there.

Tax office employees say a common question from callers is how the value of a home can go up so dramatically even when improvements haven't been made.

However, the physical condition of a house is only part of the equation. Assessments are based on fair market value, or what the house might fetch if it were to go up for sale.

If a homeowner decides to appeal an assessment, an emotional plea about how quickly the valuation has risen won't go very far. Instead, those who appeal should "arm themselves with as much sales information as they can," said Daniel Ercolani, an acting Montgomery County supervisor for Maryland's Department of Assessments and Taxation.

If similar homes in the neighborhood have recently sold for less than the disputed assessed value, a homeowner may have compelling evidence for a successful appeal, officials said.

Homeowners should also find out how assessors described their properties and point out any problems such as chronic mold or a leaky roof. Many jurisdictions provide online access to information used to calculate assessments, as well as recent neighborhood sales information. Local tax departments can also provide more information about the legal process necessary to appeal, which varies from place to place.