In the light of the old “brain drain” debate, the duty to promote poor countries’ development and the human right to emigration used to appear incompatible. In the 1970s, Jagdish Bhagwati proposed a countermeasure that would allow skilled workers to leave their poor countries, while taxing their revenues to the benefit of their home countries. This article analyzes and rejects three possible justifications of the Bhagwati tax. It concludes that the Bhagwati proposal cannot be advocated either as a compensation for what the country would have gained, had the skilled worker not left the country, or as a reciprocity obligation based on the public investment in their education, or as a way to decrease the unequal access to opportunities between migrants and those left behind. If geographical mobility goes hand in hand with social mobility, taxing migrants amounts to taxing access to opportunity, rather than the high incomes themselves.