The residence subsidy is a discount of up to 75% on the fares of regular air transport services, granted by the Spanish government.
The discount is available for citizens of Spain, European Union member states, other countries in the European Economic Area (currently Norway, Iceland and Liechtenstein) and Switzerland who can prove they are residents of the Balearic Islands, the Canary Islands, Ceuta or Melilla and are travelling between the place of residence and any destination within Spain.

The valid document for proving residence in a non-mainland part of Spain (both for Spanish citizens as well as those of the European Economic Area and Switzerland) is the residence certificate issued by the municipal council where you are registered.
For more information, check www.fomento.gob.es.