Hi Verdemar.
Options have been discussed a few times in the past week. I have been a non-resident Property owner for the past 8 years.
Tax forms can be filled in by property owners and submitted at a very small cost to the Property owner.
Just one thing to note that all Tax forms only come in Spanish.
There is a reference website on the net that explains in English on how to fill the forms out.
I have seen people on the web who offer to submit Forms for you for as little as €30.
I myself pay my Solicitor a fee to submit them for me every year. The good thing with this is that at any time I come to sell my property he will have a record of all my taxes being paid.
It can be very expensive to a Property seller who has not paid all their taxes as Back tax will be required also a fine.
If the property is in joint names each name has a tax responsibility .
Hope this helps a bit.