During the period 2004-2005, Mendis served as the Director of National Council for Economic Development at the Institute of Policy Studies (IPS) and served as the Chairman of the Sovereign Rating Committee for the Government of Sri Lanka. He was awarded the title of Deshamanya in 2005 by the Sri Lankan Government. During the same year, he also attended the opening of the Hatton National Bank's museum and decided to change interest rates despite last year's tsunami disaster.