In 1944, Jaša Tomić became part of the autonomous province of Vojvodina within the new socialist Yugoslavia. In 1945, Vojvodina became part of the People's Republic of Serbia within Yugoslavia. The German population had mostly fled from Jaša Tomić by the end of the war (in 1944), while some mainly Serb colonists from Bosnia and Herzegovina, Central Serbia and Croatia settled in the town from 1945. Post-war population censuses recorded a Serb ethnic majority in the town. Until the 1950s, Jaša Tomić was the seat of the municipality, but in 1955 this municipality was abolished and the town became part of the municipality of Zrenjanin. Later a separate municipality of Sečanj was formed and town of Jaša Tomić was included into this municipality. However, even today Jaša Tomić is the largest settlement in the Sečanj municipality and the only settlement in the municipality with town status, Sečanj, its seat, being only a village. In 2005, the town was devastated by floods.