Property tax bills are due to be paid to city, village and town treasurers by today, either in full or in half, with the other half due to county treasurers by July 31.

While property tax bills depend on a particular property’s assessed valuation, owners of property in Grant, Lafayette and Iowa counties are paying a lower tax rate this year.

According to the mil rates for the 214 taxing district combinations — county, municipality, school district and special district — in Grant, Lafayette and Iowa counties, the average mil rate for property tax bills due this year was $21.49 per $1,000 assessed valuation, down from $21.80 per $1,000 last year.

The median mil rate — halfway between highest and lowest — in those three counties also dropped, from $21.53 per $1,000 last year to $21.39 per $1,000 this year.

Property tax rate information was supplied by the Grant, Lafayette and Iowa county treasurers. The three counties’ mil rates can be found on page 6A and on the Excel files attached to this web page.

The highest property tax rate in Grant, Lafayette and Iowa counties is the Iowa County part of the Village of Muscoda. Property owners pay $30.27 per $1,000 assessed valuation.

The lowest property tax rate in Grant, Lafayette and Iowa counties is the Town of Boscobel. Property owners there pay $15.09 per $1,000 assessed valuation.

The property tax mil rate is determined by dividing the total tax levy for each unit of government — county; city, village or town; school district; technical college district (in this area’s case, Southwest Wisconsin Technical College); and special districts such as fire or sanitary sewer districts — plus the state forestry tax, divided by the total assessed valuation of the city, village or town.

The listing on page 6A shows each municipality and school district combination — including special districts where they assess additional taxes — with the 2011 and 2012 mil rates per $1,000 assessed valuation, and the property tax bill for a house assessed at $150,000 in that municipality.

Property tax bills are reduced by three credits — the school levy tax credit, which is applied to the school property tax; the first-dollar credit, and the lottery and gaming credit. The first-dollar credit applies to all property, but the lottery and gaming credit applies only to owner-occupied homes. The first-dollar credit averages $67.28, according to the state Department of Revenue. The tax bill on the hypothetical $150,000 house as listed on page 6A does not include the first-dollar credit or the lottery and gaming credit.

The largest component of property taxes is school property taxes. In Grant, Lafayette and Iowa counties, school property tax mil rates range from $8.37 per $1,000 in the Southwestern School District to $16.58 per $1,000 in the Highland School District.

County property taxes can make for different tax bills in the same municipality. Consider two hypothetical houses on West Barber Street in Livingston, one east of Wisconsin 80, one west of 80, the Grant–Iowa county line — each assessed by the village at $150,000 assessed valuation.

The house in the Iowa County part of the village would have a property tax bill of $3,825.03 before tax credits, nearly 12 percent more than the house to the west in Grant County, which would have a property tax bill of $3,415.34 before tax credits.

North of Livingston, in Montfort, the same situation applies. A house on the Grant County side assessed at $150,000 pays $3,121.84 in property taxes before tax credits, but a house on the Iowa County side pays $3,357.05 in property taxes before tax credits.

A similar situation is found in four other communities that straddle county lines. A house assessed at $150,000 in the Grant County part of Cuba City pays $3,437.62 in property taxes before tax credits, but the same-value house east of Cody Street — the approximate spot of the Grant–Lafayette county line in Cuba City — pays $3,843.24 in property taxes before tax credits. A house assessed at $150,000 in the Grant County part of Hazel Green pays $2,815.98 in property taxes before tax credits, but the same-value house in the Lafayette County part of the village pays $3,240.93 in property taxes before tax credits.

The Grant and Iowa county parts of the Village of Muscoda have a bigger property tax gap. A $150,000 house on the Grant County side pays $4,038.02 in property taxes before tax credits, but a $150,000 house on the Iowa County side pays $4,540.47 in property taxes before tax credits. A $150,000 house in the Iowa County portion of the Village of Blanchardville is assessed $3,637.01 in property taxes before tax credits, but a same-value house on the Lafayette County side of the county line is assessed $3,798.21 in property taxes before tax credits.

The City of Platteville’s property tax bills included, for the first time, a garbage fee of $60 for single-family homes and $120 for duplexes. The garbage fee is due Thursday.