TV Somanathan took over as cabinet secretary on Friday following the superannuation of Rajiv Gauba, an official statement said.
Gauba had been cabinet secretary since 2019 and completed an unprecedented five-year term.
Until recently the Union finance secretary, Somanathan was named as the next cabinet secretary on August 10 with a two-year tenure.
A 1987-batch IAS officer of the Tamil Nadu cadre, Somanathan is a qualified chartered accountant, cost accountant and company secretary.
He has held important assignments at the Centre, including as joint secretary and later as additional secretary in the Prime Minister's Office.
He also served as a joint secretary in the Union Ministry of Corporate Affairs and was deputed as director for corporate affairs at the World Bank in Washington DC.
Somanathan was holding the charge of finance secretary and secretary in the Department of Expenditure when he was named cabinet secretary.
In Tamil Nadu, he served many key positions such as managing director of the Chennai Metro Rail Corporation and secretary to the chief minister.
Somanathan was additional chief secretary and commissioner of commercial taxes during the crucial phase of the rollout of GST.
