Kaut returned for the 2019 World Junior Championships in Vancouver, British Columbia, after he was loaned during his first professional North American season within the Colorado Avalanche organization. In the opening game of the Tournament, Kaut scored and added the primary assist in a 2–1 overtime victory against Switzerland, to be named player of the game, on December 26, 2018. Helping the Czechs advance to the knockout rounds, Kaut scored the lone goal in a 3-1 elimination defeat to the United States on January 2, 2019. He was selected among the top 3 players for the Czech team in a 7th-place finish.