After La Follette was elected governor of Wisconsin, he appointed Haugen to the Tax Commission in 1901. Haugen served on the Wisconsin State Tax Commission throughout the Progressive era, from 1901 until 1921. During that time he made the commission an important part of the Progressive movement. In 1915 Haugen helped preserve the law's strength by persuading Gov. Emanuel Philipp not to transfer collection activities from the commission to local governments. From 1919 until 1920, Haugen served as president of the National Tax Association, a nonpartisan, educational association that studies tax theory and public finance. Haugen was adviser to the State of Montana Board of Equalization from 1921 to 1923. He died April 23, 1931 in Madison, Wisconsin, where he was interred in Forest Hill Cemetery.