Obligatory to owners of properties located in buildings of a residential type of collective housing and that have an antiquity above 50 years.
A residential building type of collective housing is defined as "the composite of more than one dwelling, notwithstanding that it may simultaneously contain other uses than the residential one"
In an assimilated way, are included in this typology those buildings intended to be occupied or inhabited by a group of persons who, without being a family unit, share services and submit themselves to a common system, such as hotels or residences.
As you can read above, in principle, and except it is required by regional or municipal regulations, single-family homes are excluded.
The owners of any building, irrespective of their age, are also obliged to carry out the IEE when they intend to apply for public aid to carry out conservation works, universal accessibility or energy efficiency, and always before the formalization of the corresponding application.
Autonomous or municipal regulations may require the IEE for the rest of the buildings, being able to establish specialties, depending on their location, age, typology or predominant use.
Failure to comply with the obligation to comply in a timely manner shall be considered an urban infraction, with the character and consequences attributed by the urban regulations applicable to breach of the duty to provide the report of technical inspection of buildings or equivalent, within the expressly established period
Official info here: https://iee.fomento.gob.es/