Originally barrio Banday, the poblacion of Tomas Oppus was under the jurisdiction of Malitbog. It became a municipality under Republic Act. No. 5777, sponsored by Congressman Nicanor E. Yniguez Jr. The new town was called Tomas Oppus.
The Yniguez law placed the seat of government in barrio San Isidro, but the seat of government was transferred to Banday by Mayor Agustin R. Escano, fanning the controversy as to the true and legal seat. Thus prompting the issuance of Presedential Decree No. 134 on February 12, 1973 which called for a referendum to settle the issue. Banday as the seat of government won in the referendum.
Tomas Oppus shares the bay coast with other Sogod Bay towns.