Slightly off topic, but just to clarify, whilst imputed tax is known as "non-resident tax", its actually a second home tax and payable if you have two properties here (if you're spanish for example), or a property here and a house in the UK for example (modelo 720 link).
Is that correct? because i paid non-resident tax on my house in Spain, and Spain didn't know i had property in the UK, for all Spain knew i could have been homeless, lived with relations or in a hotel, how would they know i had a UK house?.
I think my post is poorly worded. All non-residents have to pay imputed or deemed income tax - Rendimientos del Capital Inmobiliario. The point I was making is that it's not just a non-resident tax, its a second home tax, so applies to spanish tax residents who have another home as well. Its not a 100% clear, but I believe it also applies to a tax resident in Spain who also has a UK house, which will now be declared on the Modelo 720. This is from Blevins Franks
Regardless of your residence position, if you have a Spanish property that is not your main home and you are not renting out (or if you are and are not declaring the income to the Spanish authorities), the Spanish deem a notional income to arise, calculated as around 2% of the official value of the property. This income, even though it is not actual income, is taxable in Spain (at the scale rates for residents and at a flat rate of 24% in the hands of non-residents).