This article discusses a decision of the Netherlands Supreme Court of 22 December 2006 regarding the compatibility with the EC Treaty of the Court's refusal to allow the deduction of mortgage interest on an owner-occupied dwelling located in Belgium from the taxpayer's taxable income in the Netherlands (employment income). The Netherlands Supreme Court requested a preliminary ruling from the European Court of Justice (ECJ), as the question remained unanswered following the judgment of the ECJ in Ritter-Coulais. This article considers this issue as follows: (1) the facts and the dispute, (2) the decision of the Netherlands Supreme Court, (3) the background to the Netherlands characterization of Mr Renneberg as a limited resident taxpayer, (4) Mr Renneberg's access to the EC Treaty, (5) the relevance of the differences between personal allowances and negative income from the perspective of EC law, (6) the distinction between discrimination and disparity as far as it is relevant to Renneberg, (7) the possible grounds that could justify discrimination and (8) summary and conclusions.