In the case Geven v Land Nordrhein-Westfalen, how many hours was the Dutch woman in question working in Germany?
In Finanzamt Köln Altstadt v Schumacker the Court of Justice held that it contravened TFEU art 45 to deny tax benefits (e.g. for married couples, and social insurance expense deductions) to a man who worked in Germany, but was resident in Belgium when other German residents got the benefits.