It is advised to present your tax return annually if you live in Spain as a resident.To briefly describe how it works, the Hacienda (Spain’s central tax office) has fiscal information about all Spanish residents (both national and international). When you present a tax return, you are either agreeing with the fiscal information they have about you (and then you pay or receive back the relevant amount of tax) or you present documents to try to clarify and possibly reduce the amount of taxes that they believe you owe.The Hacienda has a lot of power available to it and it can access any records (both public and private) whenever it wishes. It may be possible that the Hacienda owe an individual money because they have paid too much tax, as is sometimes the case for low earners.The period to present your tax return runs from 1st April until 30th June 2021 and covers the previous tax year (2020 in this case)
It is advisable to present a tax return if 2020 was your first year as a fiscal resident in Spain. There is currently a dual tax agreement between the U.K. and Spain which ensures you will not pay tax twice.
Incomes from rentals are generally taxed in the country where the property is located.It is important to add that all tax circumstances should be assessed on an individual basis.