If you own a property in Spain, it can be either for your own use and pleasure or rented (or both).

1.-  Non rented properties

Believe it or not, if you own a non rented property in Spain you have to pay each year the Income Tax on a sort of “notional income”. I prefer to call it phantom income, because nobody sees it but the tax man. This phantom income is a percentage of the cadastral value (usually 1.1 %). On that income you apply the tax rate of 24,5 %.
Example: if the cadastral value of the property is EUR 100.000 the annual payment would be: 100,000 * 1.1 % * 24,5 % = EUR 269,5.
You also have to pay a local tax called Property Tax (“Impuesto sobre Bienes Inmuebles”). The taxable base of this tax is the cadastral value and the tax rate varies depending on the place where the property is located, but cannot exceed 1.1 % for urban properties and 0.9 % for rural ones.

2.- Rented properties

In case you rent your property you have to pay the Income Tax on the income you get from the rented property.  If you are a European Union citizen you are entitled to deduct from the gross income  all the  expenses related to that income, including financial expenses derived  from the acquisition of the property, depreciation (2 % on the value of the property excluding the value of the land), maintenance, professional fees and the like. The tax rate is also 24,5 %.
Tip: If you are not an European Union citizen the taxable base is the gross income, that is, you cannot deduct any expense. I call this discrimination.