In July 2015, NASA announced Boe as one of the first astronauts for U.S. Commercial spaceflights. Subsequently, he has started working with Boeing and SpaceX to train in their commercial crew vehicles, along with the other chosen astronauts - Sunita Williams, Robert Behnken and Doug Hurley. In August 2018 he was assigned to Boe-CFT, the first test flight of the Boeing CST-100 Starliner. On January 22, 2019, NASA announced that Boe was unable to fly due to medical reasons and replaced him with Michael Fincke.