In particular, a variety of new contractual arrangements are leading to uncertainty about the boundary between self-employment and wage employment. An example of an ambiguous case is when employed persons are working as sub-contractors (thus sharing some characteristics of the self-employed), while being economically dependent on one single client (similar to employees). Aspects of security that are directly related to the (type of) contract - such as duration of employment - are only relevant to employees, while other dimensions of security concern the self-employed.