After training as a naval officer and studying computer science at the University of the Bundeswehr in Munich, Thomas Daum served as a naval gunnery officer in the speedboat flotilla and as deputy commander of the 3rd speedboat squadron in Flensburg. He was also Head of the Information Technology Department at the Federal Office of Bundeswehr Equipment, Information Technology and In-Service Support in Koblenz. Daum was also Deputy General Manager, Chief of Staff and Chief Operating Officer of the NATO Communications and Information Agency (NCIA) in Brussels. Since 2020, he has been responsible for the management of the Cyber and Information Space organizational area.