In the dissertation, the removal of qualification problems that an employee who works and/or lives across borders may be confronted with, is discussed. This qualification issue comprises three legal problems:

1.  the non-tax recognition of a foreign supplementary pension scheme;
2.  the qualification of a payment as a tax or social security contribution;
3.   the qualification as social security (statutory pension) or as a supplementary pension scheme.

On the basis of a legal comparison between the Netherlands, Belgium and Germany, the dissertation provides guidance for policymakers at national, as well as European and international level for the removal of the qualification problems. The dissertation can be considered as a White Paper with which further substantiation is given to the widely supported (European) ambition to build up an adequate pension income and the promotion of the cross border labour mobility in the European Union.