I believe that, as a non-EU resident, you would pay 24% tax on all the rental income but you would not be eligible for tax relieve or expenses accrued. You need to check with a solicitor first but the laws were changed in 2015 because Spain discriminated against EU residents and non-residents. They are now taxed at 19% but can claim expenses for mortgages and ongoing costs. AFAIK this does not apply to non-EU citizens.
One lawyer website states There are allowances made for some expenses, but, only for tax residents in a country within the European Union, Norway and Iceland and these reduce the amount on which tax is payable. This includes a proportional part of the house insurance, IBI, the community fee, water and electricity if paid by the house owner.
A property site states:
I) Landlords resident in E.U. or E.E.A.
- Tax relief: Yes, physical persons may deduct, for example, home insurance, mortgage loan interest payments, property maintenance expenses etc. Legal persons may also deduct rental related expenses.
- Dates: collected annually or quarterly.
- Tax form: 210.
- Tax rate: 19% on rental income for 2016.
II) Landlords resident outside the E.U. or E.E.A.
- Tax relief: no.
- Dates: collected annually or quarterly.
- Tax form: 210.
- Tax rate: 24% on rental income for 2016.