A co-founder and Managing Partner in Buñag & Lotilla Law Offices, Atty. Buñag was the Bureau of Internal Revenue Commissioner in 2005. He is a tax expert with postgraduate studies in Taxation & Law. Atty. Buñag also served as BIR Deputy Commissioner in charge of the Legal inspection group from December 2002 to July 2005.  He finished his Bachelor of Laws at the Ateneo de Manila University Law School in 1968, graduating as Cum Laude & Class Valedictorian and placed second in the 1969 Bar Examination. He has also been a Senior and Managing Partner of the Roco Buñag Kapunan & Migallos Law Office, a partner of the Angara Abello Concepcion Regala & Cruz (Accra) Law Office, and its Assistant Treasurer and Counsel for the Regional Banking Group based in Indonesia & Malaysia.  He worked as Legal Editor of the Publication Securities Law of Commerce Clearing House based in New Jersey. He was also actively engaged in the academe where he served as a professor in Philosophy and also in Taxation, Criminal Procedure & Legal Philosophy at the Ateneo de Manila University. Lastly, he was also a Lecturer of the Philippine Trust Institute and the Ethics and Judicial Conduct Department of the Philippine Judicial Academy.