Kadas was born in Roseburg, Oregon in 1956. He moved to Missoula in 1979 where he was employed as a carpenter from 1983 to 1986. He was also the owner of a small construction company from 1989 to 1996. He received a Bachelor's degree in economics-philosophy in 1992 and a Master's degree in economics in 1996, both from the University of Montana. Kadas worked as the director of special projects for Rivertop Renewables from 2008 to 2012. He and his partner Martha Newell have two sons.[3]
Kadas was first elected into the Montana House of Representatives' 95th district (Missoula) in the 1982 elections as a Democrat. After redistricting, he was re-elected five times between 1984 and 1992 as the representative for the 55th district and then once again in 1994 for the 66th district following another redistricting. He won the 1996 Democratic primary for the 66th district but withdrew from the race after being appointed mayor of Missoula. Diane Sands was appointed Democratic nominee and won unopposed in November 1996.[4]
On September 3, 1996, incumbent Missoula mayor Daniel Kemmis announced his resignation, prompting the Missoula City Council to appoint Kadas to the role of mayor. He won the November 4, 1997, Missoula mayoral election and served until 2006.[5] He was credited with handling Missoula's growth with infrastructure improvements and with managing the city professionally.[6]John Engen was elected in November 2005 to succeed Kadas.[7]
Kadas was announced as the Director of the Montana Department of Revenue by Governor Steve Bullock in December 2012.[1] In April 2018, he announced he would be retiring after over five years in the position. His resignation came as the agency was closing half of its property assessment division offices and suspending new hires following budget cuts. He was credited with modernizing the state property tax appraisal process and negotiating the settlement of contested taxes.[8]
