Within the framework of the nitrate directive, member states have the possibility to apply for derogation, i.e. increasing fertilization standards under certain conditions. Several EU regions have made use of this possibility but all in a different way. In 2009, 6 different derogation policies were worked out. This paper focuses on the differences between the applied policies and makes an assessment of the impact of these differences on the application rate of derogation, the manure surplus and the costs to allocate the manure. Based on the MP-MAS model described by Van der Straeten et al. (2010) the different scenarios are applied on a single case area (Flanders) and the economic effects have been simulated. Results show large differences between the policy alternatives, leading to the conclusion that member states not only have to focus on the permission to allow derogation or not but also at the details of the derogation policy. Granting derogation at parcel level instead of farm level increases the potential effect of derogation, the height of the increase in fertilization standards under derogation determines the application rate of derogation: a higher increase leads to a higher application rate.