First Occupation License is necessary for the registration of Finished New Work Notary Deed and registration and therefore for posterior first transmissions ( from developers to buyers).
Whatever regional regulations establishes, as Notaries and Registrars and Constitutional Court in Spain have already set: competency for the determining of the necessary requisites for public documentation ( Notary deeds) and registration ( at the Land Registry) of authorisations and licenses established by regional regulations, is always National.
And National Ground Act clearly establishes the obligatory vertification of existence of First Occupation Licenses before granting of Finshed New Work deeds and its registration
So, no Notary should authorise Finished New Work Deeds and no Land Registrar should register it before veryfing on the existence on these.
An example of why a good independent lawyer--- better if locally independent too-- , with good knowledge of Real Estate, Land Registry, Urban and Horizontal Property Law is essential for a safe property purchase in Spain.
Recent history teaches us!