Tewari gave his charge to senior IRS officer and Member (Investigations) K V Chowdary, said a senior official.
Chowdary is tipped to be the next Chairman of CBDT.
Tewari, a 1976-batch IRS officer, has been at the helm for the past five months after he took over the top post on March 1.
The name of the new CBDT boss will be cleared by the Appointments Committee of the Cabinet (ACC) headed by Prime Minister Narendra Modi.
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He has earlier officiated as the Member (Audit and Judicial) before taking over the investigations charge, a post he occupied after serving as the Director General (Investigations) in the national capital where headed a number of high-profile I-T probes, including the 2G spectrum allocation case and the HSBC Geneva taxpayers list along with a number of cases dealing with blackmoney and tax evasion.
The CBDT has six members apart from the Chairman and is the apex body for framing policy and administrative issues related to direct taxes and the Income Tax department.