Butler County commissioners have adopted a $186 million spending plan that required a property tax increase of roughly 1 mill to balance it.

Under the budget for 2009, the owners of a home with a market value of $150,000 will see an $18 increase in their county property tax bill for a total of $440 this year.

Commissioners Chairman Dale Pinkerton and Commissioners James Kennedy and James Lokhaiser all voted for the 2009 budget at a special meeting Wednesday.

Effective this year, Butler County has modified its assessment system to tax real estate at 100 percent of its 1969 market value, rather than 75 percent of the 1969 value.

Under the new formula, a home with a $150,000 market value has an assessed value of $15,630, according to Ed Rupert, county director of property and revenue.

As a result of the ratio change, millage rates had to be adjusted because, under state law, counties and municipalities are limited to a 5 percent increase in revenue in the first year following a ratio change.

Commissioners set the 2009 tax rates at 19.688 mills for general expenses and 3.94 mills for debt service.

Comparable rates for 2008 were 18.75 mills and 3.75 mills.

Each mill of property tax will bring the county about $1.52 million this year.

Retired Chief Clerk William Patterson, who served as a budget consultant, warned commissioners that two factors could require revisiting the spending plan early in 2009: rising health insurance and pension costs.

The county's approximately 500 union workers last month rejected proposed labor agreements that would require them to contribute for the first time toward the cost of their health-care premiums. The rejection of those pacts will raise the county's fringe-benefit expenses by as much as $500,000.

Chief Clerk Bill O'Donnell said talks with union workers would start up again this month. If county officials conclude they will not reach a deal on sharing the insurance costs by March 31, commissioners will have to consider across-the-board budget reductions, layoffs or cuts in selected services or programs.

Unless investment returns improve in 2009, Mr. Patterson said, the county may have to pay another $100,000 into its pension funds.

Mr. Pinkerton thanked Mr. O'Donnell and Mr. Patterson for their work on the budget. He noted that the two men approached the task independently but their proposed spending plans were within $150,000 of each other.