Deputy Treasury Secretary Neal Wolin, who had also been planning to leave his post around this time, will remain in the role to facilitate the transition.
Lew has experience of handling tough political and economic situations, having served as budget director at the Office of Management and Budget under both Obama and Clinton.
He also worked as an aide to Democratic House Speaker Tip O’Neill – who was heavily involved in negotiating the last comprehensive tax reform legislation with Republican President Ronald Reagan – in the 1980s.