If your spouse or civil partner, (or simply partner if you can provide evidence that though not registered as such, you’ve been living together as a couple for a period of time); or either of your parents are Spanish or are from an EU country living in Spain and registered here, and you wish to reunite with them you may also apply (simultaneously) for residency as a family member of a Spanish or EU citizen who are allowed to have residence in Spain.
This can be a very interesting option for British citizens – post-Brexit – if either partner has access to an Irish or other EU passport, by virtue of having a parent or grandparent who was born in an EU country.
While the holder of the passport will have an automatic right to reside in Spain, their partner can use this visa application process to also reside legally in Spain. The visa also grants the right to work in Spain.