INDIANAPOLIS | If Lake County's new property tax assessments prove problematic, it won't be because of a lack of effort.

A new analysis by the Indiana Department of Local Government Finance shows local assessors updated the property values of all but 4.5 percent of the more than 18,000 commercial and industrial properties in Lake County.

That contrasts sharply with Marion County, where Gov. Mitch Daniels ordered a complete reassessment after learning local officials offered no changes for 75 percent of the county's nearly 25,000 business parcels. The apparent failure shifted tremendous tax burden to homeowners, who were socked by bills more than 35 percent larger than last year.

"Based on the data the state currently has, it appears the Lake County assessors put more effort into trending commercial and industrial properties than their counterparts in Marion County," said Ryan Kitchell, director of the state Office of Management and Budget.

The preliminary data proves Lake assessors went out and did their work. But it will be at least two months -- until tax bills go out -- before anyone can guarantee the assessments were completed correctly.

Porter County -- also eyeing a September date for mailing tax bills -- has yet to send state officials data needed to calculate how many of its business properties went unchanged in this year's reassessment, which is updating values from 1999 to 2005 levels.

Daniels has warned Marion County probably won't be the only county forced to rip up its tax bills and start over. But Democratic House Speaker Pat Bauer issued a statement Friday demanding state government shoulder the cost of any mandated reassessment.

Daniels ordered Marion County to bear the cost of its reassessment. And Lake County had to pay $24.3 million to a private firm that the state forcefully hired to conduct its 2002 reassessment.

That year, the state also took over assessment duties for Lake's largest taxpayers -- BP, Mittal Steel and U.S. Steel.

As The Times first reported Friday, the combined value of the three firms' more than $300 million in lakefront property went up just 4.7 percent this year. Still, the companies are contesting the state assessments, and Mittal and U.S. Steel will appear before the Indiana Board of Tax Review next week.

Lake County also is appealing the Mittal and U.S. Steel assessments, arguing the calculations are too low. The county is not contesting BP's assessment, which went up 16 percent, a $12.5 million increase, in tax value.