With the outbreak of the First World War, Tait joined the Royal Canadian Engineers as a sapper before being commissioned into the London Regiment of the British Army in 1916. He was seconded to the Royal Flying Corps, where he focussed on radio and aerial navigation. Transferring to the new Royal Air Force (RAF) in 1918, he was an instructor at the RAF's Electrical and Wireless School in 1919. After a period of illness Tait served with No. 4 Squadron in Constantinople from 1922 to 1924 as a pilot and wireless specialist. On his return to the United Kingdom, Tait was appointed to signals staff officer duties.