A Beloit billionaire who is Gov. Scott Walker's largest campaign donor owed no state taxes in 2010 because of a change in her corporation's structure.

State Department of Revenue records show Diane Hendricks' tax obligation dropped from $2.2 million in 2009 to zero in 2010. Hendricks owns ABC Supply Inc., the nation's largest wholesale distributor of roofing, windows and siding. Records show Hendricks had a seven-figure tax bill in four of the previous five years.

Hendricks is a financial supporter of conservative causes and has given Walker's campaign more than $500,000.

ABC Supply's tax director Scott Bianchini told the Milwaukee Journal Sentinel the company changed its structure so the profits and the tax obligations stay with the company, not with Hendricks.