Thank you to the information provided by the British Embassy:
Residence registration:
– The Spanish authorities have recently updated the the version of their guide on residence registration
While most of the changes are small tweaks, there is an important addition to the Spanish guide on p.15 – a specific question and answer on the documentation that UK nationals can present to demonstrate that they were living in Spain by 31 December 2020.
– We know one of the main reasons that residence requests are rejected or declared inadmissible (inadmitido a trámite) is because of insufficient evidence of living in Spain before the end of the transition period. The guide now provides more examples of the sort of documentation that can be accepted and highlights that applicants should provide as much information as possible. Please point those who still need to register to this information.
– The Spanish government have also now published detailed data on the Withdrawal Agreement registration process. The infographic is particularly useful/interesting in breaking down the data by province, or process.