First posting so hope it works !!
We have owned in Mijas since 2001 and discovered that we can go direct to the Torremolinas Ministerio de Hacienda in the main shopping area by the Picasso Cultural centre to collect the form 214 ....."impuesto sobre el patrimonio y sobre la renta de no residentes " which we are reliably informed is the wealth tax form for non- residents. We assume there is a local office near Casares/ Manilva. The form cost 1 euro last year and can be filled in fairly easily so long as you only have one property in Spain .
The completed form is taken to your bank for payment ,is stamped while you wait then they forward it , you keep a copy .
We were informed that the money you pay is a tax whether you rent your appartment or not and is an easy tax for the Spanish Tax collector to administer. We have been informed that any wealth tax paid should be allowable against your final capital gain when the property is sold.
We hope this information helps but must obviously advise that anyone using this system must satisfy themselves that they are happy to adopt it OR pay your lawyer to do it for you !!!
Murray.