The Número de Identidad de Extranjero, commonly known as N.I.E., refers to the Identification Number for Foreigners or Foreigner Identification Number. It is a personal, non-transferable identification number that is registered in the Spanish Central Registry of Foreigners by the General Directorate of Police and the Guardia Civil. The NIE number remains valid indefinitely and is required to be mentioned in all communications with Spanish authorities.
In various scenarios such as purchasing real estate or a vehicle, registering for water, telephone or electricity services, and particularly in relation to the Spanish state, it is essential to have an NIE number. It also serves as a tax identification number, and without it, Spanish tax authorities cannot calculate or process annual tax payments, including income tax (IRPF) and property tax (Patrimonio), which must be declared by both residents and non-residents.