When the “Brazil Without Extreme Poverty” Plan was launched, the Ministry of Social Development and Fight against Hunger – since 2016 Ministry of Social and Agrarian Development (MDSA) – needed to define an extreme poverty line as a suitable parameter for conducting an initial diagnosis of the country´s extremely poor population, as well for annually monitor the course of extreme poverty rate and to select target population which would be benefited by the Plan´s initiatives. This text explains how the extreme poverty line was defined and how it has been used to achieve results.