Prior to his election to the 16th Lok Sabha, Tamta has served as a member of the Uttarakhand Legislative Assembly, from 2007 to 2012 and again from 2012 to 2014.
He has also served in the Government of Uttarakhand, as a Cabinet Minister during 2008-09 and as an MoS during 2007-08.
As a parliamentarian, Tamta has been a member of the Committee on Welfare of Scheduled Castes and Scheduled Tribes since August 2014, and a member of Standing Committee on Human Resource Development and of Consultative Committee, Ministry of Water Resources, River Development and Ganga Rejuvenation since September 2014.