Any worker, self-employed or employed, pensioner and, in short, any person who has received income during the previous calendar year must go through this procedure, as long as they comply with certain scales shown below. 

Exceptions 

As stated by the Tax Agency, people who have had an income of less 15,000 euros  are not obliged to file the income tax return. 

This limit is 22,000 euros if there has been only one payer who witheld tax. 

In any case, it is recommended to consult the fiscal information because it may well be a negative result in favor of the person and, in this case, Hacienda would be in the obligation to refund the tax paid. 

All persons who have received more than 22,000 euros from a single payer who withheld tax or 14,000 euros from several payers are obliged to file the income tax return.  

Also Property Owners

Finally, all those who own property beside the one in which they live are also obliged to report it, even if there was no incomes coming from these property.

*If you spent more than 182 years in Spain during a calendar year, you are generally considered a tax resident. Other situation may apply according to the agreement for taxation between Spain and your home country.