NEN 4400-1 is a national standard that set requirements for temporary work businesses and contractors of work, including subcontractors, that have their registered office in the Netherlands with respect to the payment of taxes, social insurance contributions and the legitimacy of employment in the Netherlands. HR ProjectPartners has been NEN 4400-1 certified since August 2009 and is registered in the Labour Standards Register (Stichting Normering Arbeid – SNA).