Returning to the RAF during the Second World War, Tait transferred to the RAF's Technical Branch in 1940 and was promoted to air commodore. After a spell as deputy director of signals, he was appointed the director of radio in 1941, the director of RDF in 1942, when he was promoted to air vice marshal. In August 1942 Tait was made Director-General of Signals, a post he until his retirement from the Air Force in 1946. During the preparations for the D-Day landing and the invasion of Normandy, Tait was responsible for planning the attack on German radar stations and spoofing other radar.