Barangay Santo Tomas South

Classified as a mid-sized barangay, Barangay Santo Tomas South is one of the administrative divisions of Jaen in Nueva Ecija, Central Luzon, Philippines.

According to the 2020 Census of Population and Housing conducted by the Philippine Statistics Authority, Barangay Santo Tomas South had a population of 4,940. This made it the 3rd largest of 27 barangays in Jaen by population, placing it among the most populous barangays of the municipality. Residents of Barangay Santo Tomas South accounted for approximately 6.24% of the total population of Jaen, which stood at 79,189 in the same census year.

The barangay recorded 4,675 residents in the 2015 intercensal count and 4,940 residents in the 2020 Census — a net change of +5.7%, consistent with a growing settlement. The Philippine Statistics Authority classifies Barangay Santo Tomas South as rural, a designation applied to barangays with lower population density and predominantly non-built-up land use.

Jaen is a municipality comprising 27 barangays, and serves as the governing unit directly responsible for local services in Barangay Santo Tomas South, including public health, sanitation, peace and order, and civil registration. Within the wider province of Nueva Ecija, which contains 849 barangays across its component cities and municipalities, Barangay Santo Tomas South ranks 114th by 2020 population. Nueva Ecija is classified as a 1st by the Bureau of Local Government Finance, a category that reflects the province's annual regular income.

Like every Philippine barangay, Barangay Santo Tomas South is led by an elected Punong Barangay (barangay captain) supported by seven Sangguniang Barangay members (kagawads), an SK Chairperson, a Barangay Secretary, and a Barangay Treasurer. The next Barangay and Sangguniang Kabataan Elections (BSKE) are scheduled for Monday, November 2, 2026, with officials serving four-year terms under Republic Act No. 12232.