This is an Opinion Statement prepared by the ECJ Task Force of the Confédération Fiscale Européenne (CFE) on the Gielen case (C-440/08). The case concerns the optional application of business-related deductions to non-resident taxpayers and its compatibility with the freedom of establishment. Advocate General Ruiz-Jarabo Colomer delivered his Opinion on 27 October 2009 and the ECJ decided the case on 18 March 2010 in favour of the taxpayer. The CFE is the leading European association of 32 national tax advisory organisations representing over 180,000 tax advisers.