All foreigners with interests in Spain, whether or not resident, are required to declare their income.

Foreigners who own property in Spain must file an annual statement/tax return in respect of such property if it is for their own use, or a quarterly statement/return if they rent out their property. That does not mean that they have to pay tax twice if they also have to declare their property for tax purposes in their home country, since under the relevant double taxation treaty the amount declared and paid in Spain can be deducted from the amount declared and paid in the country of origin.