PHILADELPHIA (CBS) - Field inspections have begun in Philadelphia neighborhoods to capture data to conduct a reassessment of about 577,000 properties, by October of 2012.

When the new property assessments ultimately go out, City Hall concedes some property owners whose property values have grown more quickly than their tax bills will see higher tax bills.

“We don’t set the market, new chief assessment officer Richie McKeithen says. “We just follow the activity that occurs.”

He says many of Philadelphia’s row-house neighborhoods are homogeneous, so they won’t have to go into each and every home.

“You can obtain information about five, six, or seven on a block of 30, and that pretty much gives you a consensus of what might be going on with the rest of the actual block.”

He says by incorporating industry standards, their aim is to get assessment values as close to true market values as possible.

In Philadelphia, there are 423,000 residential single family homes and about 30,000 condos. The rest are multi-family complexes, mixed-use, commercial, and industrial properties.

Reported by Steve Tawa, KYW Newsradio