The Efficiency Medal was instituted in 1930 for award to part-time warrant officers, non-commissioned officers and men after twelve years of efficient service on the active list of the Militia or the Territorial Army of the United Kingdom, or of the other Auxiliary Military Forces throughout the British Empire. At the same time a clasp was instituted for award to holders of the medal upon completion of further periods of six years of efficient service.

The Efficiency Decoration, post-nominal letters TD for recipients serving in the Territorial Army of the United Kingdom or ED for those serving in the Auxiliary Military Forces, was instituted in 1930 for award to part-time officers after twenty years of service as an efficient and thoroughly capable officer. The decoration superseded the Volunteer Officers' Decoration, the Colonial Auxiliary Forces Officers' Decoration and the Territorial Decoration.