The Common Agricultural Policy post 2020 will address an increasing set of objectives, including contributing to the sustainable development goals and the Paris climate agreement. Current monitoring systems are focussed on structural and economic data and hardly cover performance indicators on the sustainability performance of farms. The EU financed FLINT project demonstrated that it is feasible to collect these sustainability data at farm level and illustrated the added value of having this type of data in a range of case studies. In this paper the costs and benefits of collecting sustainability indicators are described. Collecting the sustainability data on all farms included in FADN would increase the costs with about 40%. Large differences between countries can be observed depending on the current costs of data collection and the expected additional work to include sustainability indicators. Given the pressing need for these data a scenario is developed where sustainability data is collected on a sub-sample of 15.000 farms. This can be achieved within current budget limits if the current FADN sample would be reduced from 85 to 75 thousand farms.