AxisPhilly reviewed data for homes that sold in 2011 and 2012 and compared those prices against what city assessors say the properties are worth. Sales that weren't considered to be "market rate" and those that sold for less than $30,000 were not used. As part of the Actual Value Initiative, a move to a new property-tax system based on market values, the city reassessed more than 579,000 properties - some that had not been assessed in years.
"It sounds to me as though there might be an issue with the accuracy of the square-footage data that the city has on record for these buildings," said Robert Taylor Sr., president of the Independent Association of Assessment Officers. Taylor said that sometimes assessments are thrown off because city records about whether a building has been renovated are not accurate.
Typically, he said, assessors take a square footage of a property and multiply that by an average price per square foot for similar properties in that market area to come up with an estimate of value.
"In order to validate this analysis, we would need to further study and analyze it, and right now we don't have the time to do that," said Curt Heintzelman, a spokesman for the Office of Property Assessment. "We're concentrating on getting the assessments out and correct."
Mayoral spokesman Mark McDonald said that the administration did not have any concerns about a systematic problem with the assessments.
City Councilman Mark Squilla, who represents the 1st District, which includes parts of South Philly, Northern Liberties, Fishtown and Center City, said that his office received about 300 calls regarding the accuracy of the assessments. He has told people to file a first-level review with OPA.
"There are a whole lot of numbers that are off," Squilla said. "I don't think we should move forward unless we can phase it in over time." The 80-to-120 percent range is not hard and fast, Taylor said. Some states have adopted different ranges as a standard, but they are usually more narrow. "It's a generally accepted standard," he said.
AxisPhilly also mapped the data it developed to allow you to explore your neighborhood. In stable neighborhoods with a reasonable number of transactions, the assessments are generally within an acceptable range of sale prices. In more rapidly changing neighborhoods, with transactions more spread out, more variances appear.
- Daily News staff writers
Jan Ransom and Sean Collins Walsh contributed to this report.
sales-price-versus-assessments/ to check out a map by AxisPhilly.
On Twitter: @Jan_Ransom