Annex 1 aircraft registered in other EU states can fly here all year round, subject to submitting a declaration, so no approval is required
Is it a declaration per flight, per year or once off?
I read a bit but couldn’t figure that out. I think I need to register to figure that bit out.
They use the following definition: ULM, historical aircraft and aircraft built by amateurs registered in other States that do not comply with ICAO Annex 8.
Exactly, so a Super Cub or so which is still an a CofA of course still won’t not need this authorisation.
Aart, on a quick read, it still seems a bit convoluted, especially that one has to gain access to some portal over which the declaration / application then has to be submitted.
Anyway, it is a good thing that they now clarify that (for EU-reg. aircraft) it is merely a declaration, and therefore now reply is needed.
Is it a declaration per flight, per year or once off?
I also wondered, and I think you are right that seeing the form would make that clear.
Looking at the form it does not become entirely clear.. It mentions a start date and an end date, a route or a base. So for an incidental visit it’s clear what to do. As to what to fill in if one wants to permanently station a plane in Spain, it’s not clear. Again, I have not been able to find anything in these documents that prohibits that. I thought about mailing them to clarify, but it is maybe better to not wake up a sleeping dog 
