In Spain, taxpayers are required to file tax returns on their own without any reminder from the tax office, unlike in Germany where taxpayers receive guidance for "Veranlagung."
Whether a Spanish resident or non-resident, the taxpayer is responsible for determining which tax returns to file among almost a hundred different tax returns (known as Modelos), and preparing and submitting them within the given deadlines.
Additionally, the payment of the calculated tax burden must be made to the tax office, with a corresponding payment voucher issued by banking institutions. The Spanish tax office does not provide any assessment notice or communication regarding the tax return filing or payment of taxes.
Thus, it is essential to keep electronic proof of filing and bank confirmation of payment as evidence of tax compliance.