wrote on Jun 6^th, 2015 at 2:05pm:

If you are a non-resident property owner in Spain and you don't rent it out, then you don't pay income tax in Spain. You pay local taxes related to your house. Register in the town where your house is located and they put you in the system for local taxes. As a non-resident you don't need to file a tax return when you don't rent out your house and you don't have a business in Spain.

You need a fiscal advisor as advised hereon. Here is what I found with regards the above advice.

Income tax for non-residents who do not rent out their property (standard declaration)
Spanish name      Impuesto de la renta de no residentes, declaración ordinaria (IRNR)
Description      You pay this version of income tax in Spain if the following conditions apply: 1) You do not reside in Spain, 2) You own property in Spain, 3) The property is exclusively for personal use and you do not rent it out, 4) You have no other source of taxable income in Spain. Although you do not earn an income from the property, in the eyes of the Spanish tax authorities you still derive a benefit from owning a property in Spain and therefore have to pay an imputed income tax.
Tax base and rate      Tax base: 2% of the cadastral value of the property (found on the IBI receipt), or 1.1% if the cadastral value has been revised since 1st January 1994. Tax rate: 24% (temporarily increased to 24.75% for 2012 &2013). It used to be 25% in 2006 and before.
Form      Use general section 210-A and indicating income type 02.
Dates      Presented before the 30th June each year. For example you have from 1st January to 30th June 2006 to declare tax on income during 2005.
Example      Cadastral value of property = 200,000 Euros
Base = 2,200 Euros
Tax = 24% x 2,200 Euros = 528 Euros (or 24.75onio (Patrimonio)
This tax was eliminated as from 01/01/2008, then reintroduced in September 2011 for the years 20011 & 2012, then extended to 2013, with several important changes and other issues that are explained in depth in the sectiolue of their assets in Spain after permitted deductions, such as mortgages. This tax is collected by regional governments.
Tax base and rate      The tax is based on the net value of you property (less mortgage, if any) or another value deemed appropriate by the tax authorities, with a tax-free allowance of €700,000. The tax rate works on a sliding scale with marginal rates starting at 0.2% and rising to 2.5%.
Form      714
Dates      Presented in June for previous calendar year.
Example      Depends upon the autonomous region where your property is located. No wealth-tax to pay in most regions if the net value of your property does not exceed €700,000
Income tax for non-residents who do not rent out their properties, combined with the wealth tax
Spanish name      Impuesto de la renta de no residentes, y Patrimonio (IRNR y Patrimonio)
Note: See changes to the ‘patrimonio’ wealth tax above. Until the wealth tax situation is clarified it is hard to say if this form will be brought back. But it is likely that, for most non-residents, the form 210 (see above ‘Declaración ordinaria Impuesto sobre la Renta de no Residentes’) will suffice for 2011 and 2012.
Description      Under certain conditions non-residents can pay the two taxes mentioned above (IRNR and Patrimonio) in the same declaration and using the same form. Therefore this is not an extra tax, just a more convenient way of paying the two taxes previously mentioned. To present these taxes together in the same form you have to meet the following conditions: 1) You do not reside in Spain 2) you only own one property in Spain, and 3) this property is exclusively for personal use and is not rented out.
Tax base and rate      The value of the tax is the sum of the two taxes as explained above.
Form      214
Dates      Presented any time during the following calendar year, deadline 31 December. So you present in 2013 for taxes in 2012.
Example      N/A
Income tax for non-residents who rent out their property
Spanish name      Impuesto de la renta de no residentes, declaración ordinaria (IRNR)
Description      If you 1) do not reside in Spain 2) own property in Spain and 3) rent out your property, you have to pay income tax on the rent instead of the imputed tax described above. (If you rent out your property to a Spanish company the company will deduct tax at source and pay it to the tax authorities. Under these circumstances a nonresident is not obliged to present the forms 210 or 215.) (reference)
Tax base and rate      The tax base is the net rent, deductions of expenses allowed (since 01/01/2010), and the Tax rate: 24% (temporarily increased to 24.75% for 2012 &2013). It used to be 25% in 2006 and before.
Form      210 (use general section 210-A and indicating income type 01) or 215
Dates      210 = Monthly, one month after rent is due
215 = Quarterly, in the first 20 days of the month following the end of the quarter.
Example      Annual net rental income of 20,000 Euros
Tax @24% = €4,800 (@24.75% in 2012/2013 = €4,950)
Municipal property tax
Spanish name      Impuesto sobre Bienes Inmuebles (IBI)
Description      This tax is the Spanish equivalent of the rates and is collected by local government.
Tax base and rate      The tax base is the cadastral value of the property and the rate varies from 0.405% to 1.166% depending upon the region. The following table shows rates per regions, and the year in which the cadastral value was lasted updated.

Form      N/A
Dates      Payment period determined by the local authority.
Example      Varies, but 200 Euros – 800 Euros per annum will be common.
NOTES
Cadastral value      The cadastral value (valor catastral) is the rateable value of a
Income tax for non-residents who do not rent out their property (standard declaration)
Spanish name      Impuesto de la renta de no residentes, declaración ordinaria (IRNR)
Description      You pay this version of income tax in Spain if the following conditions apply: 1) You do not reside in Spain, 2) You own property in Spain, 3) The property is exclusively for personal use and you do not rent it out, 4) You have no other source of taxable income in Spain. Although you do not earn an income from the property, in the eyes of the Spanish tax authorities you still derive a benefit from owning a property in Spain and therefore have to pay an imputed income tax.
Tax base and rate      Tax base: 2% of the cadastral value of the property (found on the IBI receipt), or 1.1% if the cadastral value has been revised since 1st January 1994. Tax rate: 24% (temporarily increased to 24.75% for 2012 &2013). It used to be 25% in 2006 and before.
Form      Use general section 210-A and indicating income type 02.
Dates      Presented before the 30th June each year. For example you have from 1st January to 30th June 2006 to declare tax on income during 2005.
Example      Cadastral value of property = 200,000 Euros
Base = 2,200 Euros
Tax = 24% x 2,200 Euros = 528 Euros (or 24.75% x €2,200 = €544.50 in 2012 & 2013)
Spanish name      Impuesto sobre el Patrimonio (Patrimonio)