Are you a non resident who owns a holiday home in Spain which you they rent out?
The rental income of non Spanish residents should be declared in Spain even it is properly declared in the country where you are tax resident (e.g. the UK which does expect its residents to declare any income from holiday rentals).
Are you a Spanish tax resident who rent out a property other than their home?
If you have a property you rent out in Spain and live in Spain yourself you will have to declare the income on your Spanish tax return (declaracion de la renta de las personas fisicas) every year, in the May-June period following the year of the rental i.e. in arrears.
The tax treatment is generous for residents. If you would like to know more about this matter, please contact us on with your query.