Tahu is the incoming Co-Director of Ngā Pae o te Māramatanga and is Professor of Demography at the National Institute of Demographic and Economic Analysis, University of Waikato. She specialises in Māori and Indigenous demographic research and has written extensively on issues of Māori population change, Māori identity, official statistics and ethnic and racial classification.

She is a founding member of the Māori Data Sovereignty Network Te Mana Raraunga and the Global Indigenous Data Alliance. She co-edited the landmark book Indigenous Data Sovereignty: Toward an Agenda (ANU Press) and a forthcoming edited volume Indigenous Data Sovereignty and Policy (Routledge).Tahu has undertaken research for numerous iwi, Māori communities, and Government agencies, and is a member of the Chief Science Advisor Forum. She was formerly a journalist and has degrees in History, Demography and Sociology from The University of Waikato and Stanford University.