How do I avoid double taxation on my Spanish property?

The primary mechanism for avoiding double taxation is the double taxation agreement (DTA) between Spain and the owner's country of residence. Most DTAs avoid double taxation on property income through crediting or national relief mechanisms: Spain taxes the income from the Spanish property via the Modelo 210. The owner reports the same income in their home-country tax return. The home country takes into account the tax actually paid in Spain. No double payment arises — provided the filing in both countries is correct. The prerequisite for the credit in the home country is proof of the Spanish tax payment. That proof is the Justificante — the official filing receipt issued by the AEAT after successful submission of the Modelo 210. The Justificante contains the NRC (Numero de Referencia Completo), the amount paid and the tax year. This document must accompany the home-country tax return or be retained as evidence. When filing through Fiscaro, the Justificante is generated automatically and made available for download — it serves as tax documentation for the home-country return. In Germany, the Spanish income is reported in Anlage AUS, and the Spanish tax is credited. The Progressionsvorbehalt may increase the German rate on other income. In Austria, the credit operates analogously. In Switzerland, the IRNR is credited at cantonal and federal level. In the United Kingdom, the credit is claimed via the Foreign Tax Credit in the Self Assessment return. In the United States, the credit is taken through Form 1116. A practical point: an owner who does not file the Modelo 210 and pays no Spanish tax has no Justificante — and cannot claim a credit in the home country. Correct filing in Spain is therefore not only a Spanish obligation but also a prerequisite for tax optimisation at home.