On 4 July 2018, the Court of Justice of the European Union ruled in Case C-28/17 NN A/S v. Skatteministeriet on the compatibility of paragraph 31(2)(2) of the Danish Corporate Income Tax Code with the freedom of establishment (Article 49 of the Treaty on the Functioning of the European Union). Under this rule, a loss incurred by a Danish permanent establishment in Denmark could be deducted in Denmark only if such a loss could not be used for purposes of foreign taxation. In this contribution, the authors provide a summary of the CJEU judgment in NN and focus on some selected aspects of the CJEU judgment, i.e. (1) the difference of the NN case with the Philips Electronics case (C-18/11), (2) the ‘removable’ difference in treatment, (3) the ‘conditional’ objective comparability assessment, (4) the risk of the double use of losses as an overriding reason in the public interest and (5) the reference of the CJEU to losses that are practically impossible to be deducted abroad.