The TIE card is an identity card for those residing in Spain from outside the EU/EEA. All Brits living in Spain will be able to and must obtain one, once the UK has left the EU, but there will be a grace period implemented so the process can be completed. Once the grace period has started, more instructions on how to obtain a TIE card will be available and the process for each category will be made clear.
Despite having to obtain the TIE card eventually, those who do not currently hold an EU residency certificate are still being urged to get one. Appointments have been made available (around 180 new ones daily) for the main Extranjeria office in Alicante. EU residency certificates for Brits cannot be obtained in any other Extranjeria department in the area currently.
Those who currently (or will in the near future) hold an EU residency certificate will be broken into categories to obtain the TIE card. The two main ones are temporary residency and permanent residency.
Temporary EU certificate holders
Those with temporary residency, which is the first 5 years after obtaining the certificate, will most likely go on to temporary residency with the TIE, until they have reached 5 years living continuously in Spain, at which point, a permanent residency TIE would be issued with a follow up appointment.
If, for example, you have had the EU residency certificate for 2 years at the time of your TIE card appointment, you will be issued with a 3 year temporary TIE card, at which point, after 3 years, you will need to renew it for a permanent one.
Permanent EU certificate holders
Those who hold a permanent EU residency certificate (5+ years of living in Spain), should only have to swap it for the permanent TIE card. Ensure that if you have had your EU certificate for 5 or more years, it states permanent (Permanente) on it.
Schengen area rules
Additionally, residents and non-residents, will also have to ensure they abide by the strict Schengen area rules once the UK has left the EU. If you are a legal resident of Spain, your restriction on movement in the EU does not apply for travel between Spain and the UK, but will effect travelling for long periods to other EU countries.
In compliance with the Schengen rules, non- EU citizens can only stay a maximum of 90 days in a 180 day period in ALL EU/EEA countries. Non- residents of Spain (or another EU country) must ensure they comply with these rules to avoid fines and travel bans.
https://www.citizensadvice.org.es/no-deal-instructions-for-residents-contingency-plan-follow-up/
https://ec.europa.eu/home-affairs/what-we-do/policies/borders-and-visas/schengen_en