Allegheny County may be going through its first reassessment in three years, but Christopher Koman, a Ross doctor, feels as if he's going through the second one in two months.

Koman, his pregnant wife and his young daughter moved from a modest townhouse into a 4,000-square-foot home on Radcliff Drive last year. This summer, the North Hills School District persuaded the county's assessment appeals board to bump the property's assessment from $363,500 to $450,000, the sales price.

Then Koman saw his home's assessed value shoot up another 6.8 percent -- $30,700 -- under the preliminary 2006 assessments posted on the county's real estate Web site last week. Meanwhile, the homes of many of Koman's neighbors received much lower assessed values.

"I'm willing to pay my fair share in taxes, but I just feel like I'm being double dipped," Koman said. "I feel like I've been penalized for purchasing a home."

He isn't alone. A sampling of new values from the county Web site shows many new homeowners with higher assessments than their neighbors, even if properties are identical, a fact that caused some critics to question the uniformity of county Chief Executive Dan Onorato's latest 2006 assessment plan.

Municipalities and school districts often appeal as soon as they see a discrepancy between a recent sales price and an assessed value. And they win almost all of the time, according to Noah Fardo, a partner at a Shadyside law firm that represents residential and commercial property owners.

"The school districts just walk in there with the deed," Fardo said, "and the people who really come out the worst are people who recently purchased a home."

This year alone, more than 9,000 appeals have been filed with the county Board of Property Assessment Appeals and Review. Municipalities and school districts have filed most of those, often because of new sales, according to Jerry Y. Speer, the appeals board's acting chairman.

After unveiling his plan last week, Onorato asserted that his new set of numbers is better than the numbers in an earlier reassessment attempt this year because they take into account tens of thousands of appeal results since 2002.

The result was an average increase of 5.8 percent -- instead of the average of 19 percent posted in March -- for 500,000 residential properties.

But it appears that Onorato's current numbers do not address many of the value differences for new homeowners and their neighbors.

Two South Fayette properties, for instance, share equally the same duplex, but one half has an assessed value of $268,000, while the other has a value of $205,000. The main reason for the difference: the property with the higher value was purchased in 2003, and the South Fayette School District appealed to get the purchase price.

County and local officials have long argued about who is to blame for this phenomenon. Onorato says that taxing bodies shouldn't try to seek revenue from increasing assessment values, and he has been pushing the state Legislature to stop those bodies from receiving reassessment windfalls.

But some local officials counter that the county needs to provide assessments that are more accurate. Otherwise, taxing bodies must pursue recent sales.

"The question is, what would your home sell for right now? It shouldn't be the school district's responsibility to find out. We're not in the business of assessing property," said Linda Hippert, South Fayette superintendent. "That's the county's responsibility."

Some critics say Onorato's new reassessment methodology fails to meet that responsibility.

"It may make the assessments more inequitable," said Wayne Biernacki, a veteran property appraiser and president of Real Estate Tax Consultants.

But, if new homeowners find their adjusted values to be too far out of line, they can always appeal. Under Onorato's plan, which still must be approved by County Council, the filing deadline will be Nov. 18.

The chief executive has asked the appeals board to consider his new methodology when considering appeals.

"That's something that's definitely under discussion by the appeals board," Speer said. "I don't know where it will go."

Ira Weiss, solicitor for Pittsburgh Public Schools and many suburban school districts, still wants to see more specific information about Onorato's methodology before he makes a judgment about the new numbers.

"We've seen many unexplained numbers," he said. "It does not appear, at least anecdotally, that appeal results were used in all cases."