The Chester County commissioners yesterday approved a 4.2 percent property-tax increase for 2009 after the two Republicans, calling the $554 million budget a responsible plan, spurned efforts by the lone Democrat to lower the increase.

The budget passed, 2-1.

The commissioners said the tax hike was entirely due to an unexpectedly high increase in the mandated contribution to the county pension plan. The stock market's collapse has resulted in a jump from $7.5 million this year to $13.2 million next year.

For a property assessed at the county average of $193,836, the tax will rise $31.21, to $768.56.

Democrat Kathi Cozzone, a former corporate controller, said she had "crunched these numbers six ways from Sunday" and had identified ways to cut the 4.2 percent increase by more than a third without sacrificing services.

The budget does not include savings from a hiring freeze, she said. The county could sell a number of rental properties it owns. And she called for taking $500,000 from a couple of reserve funds, including the county's $16.7 million fund balance.

But her ideas failed to sway her colleagues. Terence Farrell said that the commissioners and their staff had reduced the budget twice already, and that tapping into the fund balance could affect the county's AAA bond rating, raising borrowing costs.

"If we cut any further, the people of Chester County will suffer," he said. "We've done the best we can given the circumstances."

Chairwoman Carol Aichele called the spending plan "responsible and transparent." If it had not been for the mandated contribution to the pension plan, there would be no tax increase at all, she said.

Contact staff writer Nancy Petersen at 610-701-7602 or npetersen@phillynews.com.