We ask for your secondary school diploma for two reasons. The first being that it is good practice in the world of credential evaluation to always ask for the underlying diploma when evaluating an academic credential. This gives additional insight into the academic career of an applicant and can tell us more about the level of the bachelor diploma. The second reason has to do with fraud prevention. The more documents someone has to fabricate, the greater the chance that they will be discovered.  Students who completed their secondary school in the Netherlands (havo or vwo) do not need to submit these documents. They will be verified by DUO when you register in Studielink.