PITTSBURGH -- Property taxes in Allegheny County are taking center stage as Chief Executive Dan Onorato comes out swinging against accusations that the county's assessment system is cheating school districts and municipalities.

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Since 2003 Allegheny County filed more than 10,000 appeals on behalf of homeowners that resulted in $800 million in savings for home owners. Or, lost revenue for the county, depending on how you see it.

Onorato says he simply went after instances where school districts and municipalities ignored the 2002 baseline method of assessment and instead reassessed property based on recent sales.

"It is a green light for the districts and municipalities to use it as a backdoor tax increase" said Onorato.

Onorato said that backdoor tax increase is illegal and he said that's why the county won 8,700 of the 10,000 appeals filed during a four year period.

"We took all of the property that saw their assessed value go up because school districts chased sale prices, and we appealed on their behalf," said Onorato.

Critics say the 2002 baseline method is antiquated, lacks flexibility and isn't fair. Onorato said it is fair, has prevented property tax increases for six years and he will fight to keep it this way.

"I've instructed the county manager to go and see if property has been adjusted based on sale prices. If they have, we will continue to file appeals on behalf of the taxpayers," Onorato said.

And Onorato had a parting shot to school districts.

"Quit filing appeals based on sales, because you're not going to win. And we're going to take you head on if you try to do it," Onorato said.