Went to co-op the other day to enquire about registering olive trees for subsidy and was directed to the bank who then informed me that i must go to darp next year in either feb march or april or it could be all of these 3 months as they were not sure .  Apparentley DARP is the ministry for agriculture and fishing  and should be located in Plaza Alfonso Tortosa next to Bank of Madrid (Caja Madrid - with the green bear - DARP is the same office you get fishing licences from, big door to the left of Caja Madrid - Nigel). Hope this is some help . I presume you take your receipts for the harvest to prove your are farming the trees