This study explores the ‘brain drain’ explanation for the concentration of incomes in Canada during the past thirty years, namely, that high-skilled Canadians have made use of the high salaries on offer in the United States to extract higher salaries at home. If this is the case, then for a given level of US salaries, the threat to accept outside offers should be more credible when the Canadian dollar is depreciating against the US dollar, and weaker when the Canadian dollar is appreciating. The data are broadly consistent with this claim: income concentration worsened during the depreciations of the 1980s and 1990s, and eased when the Canadian dollar began to appreciate in value. The paper develops a simple two-parameter model based on the propositions that high earners in Canada can use US salaries to bargain for higher salaries, and that Canadian high earners can shelter part of their income from personal income taxes. It also offers some preliminary evidence about the parameter values consistent with available data. The results suggest that higher top marginal personal income tax rates may actually accentuate top-end after-tax income inequality. If high earners are able to use their bargaining power to extract pay increases to offset higher tax rates, the the burden of increased taxes will be pushed down to those lower down in the income distribution, leaving the after-tax income distribution more unequal than it was before.