Tin Sum is one of the 36 constituencies of the Sha Tin District Council. The seat elects one member of the council every four years. It was first created in Hong Kong district boards election, 1985 and had hold by Choy Kan-pui for more than a decade. It was held by the then legislator Lau Kong-wah of the DAB and Civil Force between 2011 and 2012 before Lau was appointed as Undersecretary for Constitutional and Mainland Affairs Bureau by the Hong Kong government and resigned as district councillor. The constituency boundary is loosely based on the Tin Sum village and Lung Hang Estate.