経済協力局
In 1938, Kohler entered public service, as the controller of the Tennessee Valley Authority, a position he held until 1941. During World War II, he worked in the Office of Emergency Management and War Production Board, and the Petroleum Administration for War. He received the Gold Medal of the American Institute of Certified Public Accountants in 1945. He was controller of the Economic Cooperation Administration, which oversaw the Marshall Plan, in 1948 and 1949, but otherwise worked as a private consultant in the postwar period.