Mandanas started out by working for different companies. He was a supervisor of the Carlos J. Valdes & Co.. From 1963 to 1965. He then served as an executive assistant to the president of the Far East Bank and Trust Company. In 1972, he was the president of the Fereit Realty Development Corporation until 1975 and as the Philippine Commercial Delegate of the Banque Francaise Du Commerce Exterior from 1975 to 1978. Then he became the managing director of the Manila & Hong Kong Capital Corporation from 1980 until 1987. He also served as the director for: Alpa Asia Hotels & Resorts Incorporated; United States Capital Corporation; Philippines-China Development Corporation; Oriental Pacific Equities ; Manila Taiwan Development Corporation; Apex Mining and Exploration Company and Rural Bank of Batangas. From 1987 to 1985 he also was the chairperson and president of the: Omnivest; Hedge Issues Management; Abacus Consolidated Holdings; Suricon Resources Corp.; and HIM Management Corp.
Government Sector
After the issuance of the Presidential Decree No. 1396, Mandanas served as the 1st general manager of the Human Settlements Development Corporation under former president Ferdinand Marcos. From 1995 to 2004, he served as Governor of the Province of Batangas and concurrently became president of Federation of Regional Development Council of the Philippines. He also served as chairman of the Regional Development Council from 1995 to 2004, Regional Peace and Order Council from 1995 to 2001 and from 2003 to 2004 and CALABARZON Coordinating Council from 2001 to 2004.
Committee membership
WAYS AND MEANS – former chairman ECONOMIC AFFAIRS – vice-chairperson BANKS AND FINANCIAL INTERMEDIARIES – member for the majority BASES CONVERSION – member for the majority EAST ASEAN GROWTH AREA – member for the mjority ENERGY – member for the majority FOREIGN AFFAIRS – member for the majority GLOBALIZATION AND WTO – member for the majority GOVERNMENT ENTERPRISES AND PRIVATIZATION – member for the majority JUSTICE – deputized member MILLENNIUM DEVELOPMENT GOALS – member for the majority NATIONAL DEFENSE AND SECURITY – member for the majority TRADE AND INDUSTRY – member for the majority
Congressional Oversight Committee on
COMPREHENSIVE TAX REFORM PROGRAM – former chairman PHYSICAL EXAMINATION OF IMPORTED ARTICLES – former chairman OFFICIAL DEVELOPMENT ASSISTANCE – former chairman SAFEGUARD MEASURES ACT – former member
Awards/citations received
PHILCONSA's MEDAL OF WISDOM AND COURAGE AWARDEE Phil. Constitution Association February 8, 2012 2006 DANGAL NG PILIPINAS AWARDEE Consumers Union of the Philippines 2005 REGIONAL KABALIKAT AWARDEE Technical Education & Skills Development Authority 2004, 2005,2006 2007 2008 2009 MOST OUTSTANDING CONGRESSMAN Makati Graduate School, Congress Magazine, MV Gallego Foundation 2004 OUTSTANDING PUBLIC OFFICIAL Consumer's Union of the Philippines 15th Annual National Consumers Award OUTSTANDING GOVERNOR AWARD 2nd Local Government Leadership Award Senate, Republic of the Philippines 2002 and 2003 GAWAD PARANGAL AWARDEE MOST OUTSTANDING PROVINCIAL GOVERNOR 7TH National Social Welfare and Development Forum October 2003 2002 PROVINCIAL NUTRITION GREEN BANNER AWARDEE IN THE CALABARZON REGION National Nutrition Council – CALABARZON Region September 2003 MOST OUTSTANDING GOVERNOR OF THE PHILIPPINES Awarded by PNP Maritime 2002 KABALIKAT AWARDS 2000 TESDA MOST OUTSTANDING GOVERNOR OF CALABARZON Leader Magazine July 9, 2000
Achievements
The first governor to give honorarium to Barangay Health Workers, Barangay Nutrition's Scholars, Barangay Service Point Officers, Barangay Tanod etc.
He was also the first to give PhilHealth benefits to Barangay Health Workers, Barangay Nutrition's Scholars, Barangay Service Point Officers, Barangay Tanod etc.
He was also the first to grant scholarships to deserving students.
