While his original proposal to cap property assessment increases is in court, Allegheny County Chief Executive Dan Onorato has proposed a revised method for determining values for 2006.

Onorato is sticking to his promise not to use the original 2006 assessment values, which would have caused an average countywide increase of 20 percent.

Instead, he's ordering a complete reassessment -- this time with a slight twist.

The county might have to wait a year or more for appeals courts to decide on Onorato's proposal to limit assessment increases to 4 percent. Common Pleas Court overturned the proposal as unconstitutional, but Onorato is appealing the ruling to Commonwealth Court.

Under Onorato's new plan, county assessors will once again use complex computer models that balance market conditions, recent property sales, and other factors to determine values for more than 550,000 properties. But this reassessment also will include results of the hundreds of thousands of appeals filed since the county did its last two reassessments, in 2001 and 2002.

Typically, a reassessment discards old appeal results because it relies on current real estate market conditions. In theory, old appeals shouldn't matter because a reassessment represents a snapshot of the present marketplace.

"You should let the data and statistical methodology estimate values for properties that didn't sell," said Robert Strauss, a professor of economics and public policy at Carnegie Mellon University.

Theory, however, doesn't always apply to the real world, Onorato has said. He thinks throwing out the appeals data is a fatal flaw with the current assessment system and he hopes to change that. "All the corrections that get made in the appeals, they get lost," he said yesterday.

When he announced his new plan during a news conference on Thursday, Onorato said he would use the 2002 reassessment as a "base year."

But that term is just a technicality, he said. Unlike Butler County, which uses 1969, the last time it did a reassessment, as a base year, Allegheny County would be using current market conditions to establish a new set of property values.

"They adopt a base year and freeze," Onorato said of surrounding counties. "I'm using a base year as a starting point."

Some longtime assessment observers were noncommittal in their opinions of Onorato's new plan and opted to wait to see what type of detailed proposal he sends to Allegheny County Council.

Jeffrey S. Blum, a state and local tax lawyer with Buchanan Ingersoll and past president of the tax division of the Pennsylvania Bar Association, said state law allows counties to assess property either by sticking with a base year or using fair market values.

"There's no provision for a hybrid," he said.

Reassessments aren't supposed to need appeals results, he said, but doing a reassessment is an imperfect process.

"It's not easy," he said. "Nobody is ever happy with the results."

Strauss argued that using appeals results will not necessarily improve the reassessment.

"The appeals process itself can be defective," he said. "There's nothing sacrosanct about what an appeals officer or a judge says."

Onorato discounts that argument. He says his critics told him to rely on the appeals process to fix mistakes in the now-defunct 2006 numbers, rather than imposing a cap. "They can't have it both ways," he said.

Onorato hopes to send new legislation to County Council soon. Part of that legislation would change the county's administrative code so that it no longer holds assessments to standards set by the International Association of Assessing Officers. Instead, the county would have to abide by more general "accepted assessment standards," a phrase used in the county's home rule charter.

Jerry Y. Speer, acting chairman of the county Board of Property Assessment Appeals and Review, said the IAAO standards reflect a rough average that can overvalue more expensive properties and undervalue less expensive properties.

"They skew the values," said Speer, a real estate broker who was appointed by council to the appeals board in 2000. "But that's the best you can do for a mass appraisal, because you can't go out and visit every property."

Onorato said he plans to get a Philadelphia law firm to argue the county's appeal in Commonwealth Court for no fee.

This week, Commonwealth Court underscored how long the appeals process can take when it affirmed a previous decision by Common Pleas Judge R. Stanton Wettick Jr., going back to 1999, to impose across-the-board 2 percent assessment increases for all county properties. A group of taxpayers had contested Wettick's ruling and called for a refund but the appeals court said no.