She has also assumed key positions in the Department of Finance, including Undersecretary for International Finance Group from July 2007 to November 2012, Chief-of-Staff from July 2005 to June 2010 and Director for International Finance Group from September 1995 to August 1998. She served as an Advisor to the Executive Director of the Asian Development Bank from August 1998 to August 2004.

 As the Undersecretary for the International Finance Group, she task-managed several landmark transactions including the issuance of the Global Peso Notes, as well as several Liability Management Exercises to reduce funding costs, extend maturity profiles and re-denominate foreign exchange liabilities to the local currency. Ms. De Leon has represented the Department of Finance in many international fund mobilization activities for public sector entities, formulated National Government borrowing strategies, and appropriate credit enhancements to access the least-cost financing options.

As the National Treasurer in 2013, Ms. De Leon also led the implementation of the Treasury Single Account (TSA) as part of the Public Financial Management reforms initiated by the government. The TSA made it easier to manage the cash holdings of the National Government, thereby, improving the efficiency of Treasury operations.

Ms. De Leon earned her Master of Arts in Development Economics from Williams College, Massachusetts, USA.