If a person is a non-resident in Spain (lives in Spain for less than 182 days a year in the country) but owns a Spanish property, the person is liable to pay the Spanish Non-resident Income Tax.
If the non-resident property owner does not rent their home, the Spanish tax office will assume that the owner has what is called a “Deemed Rental Income” which is subject to pay Non-resident Income Tax. This is calculated by applying 1.1% of the Cadastral value of the property (it can be found on the IBI receipt and is usually lower than the price reflected on the title deeds), on this base amount the rate of 19% is applied for European Union Citizens and a 24% for the non-European Union Citizens.
If the non-resident property owner does rent the property out, rate applicable is based on the net rent obtained, which 19% is applied for European Union Citizens and a 24% for the non-European Union Citizens.
Pro Tip:  European Union citizens can deduct the expenses incurred during the period the property was rented out, some of these include: services such as water and electricity, community fees, home insurance, council tax, waste collection tax, maintenance costs, cleaning services, mortgage interests, estate agent´s fees, solicitor´s or accountant´s fees for dealing with the income tax returns, as well as a 3% annual building depreciation.