Currently, EU nationals do not require documents to prove their right to live and work in the UK. Most EU nationals who have been in the UK for a continuous period of 5 years or more will have automatically acquired "permanent residence" status. These rights will not be recognised in the same way post-Brexit.
Once the UK has officially left the EU, the government has indicated that they will create new rights in UK law for "qualifying" EU citizens who are resident in the UK to confirm their settled status.
To "qualify", EU citizens must have been resident in the UK before a specified date and have lived in the UK for a continuous 5 year period. The specified date has not yet been confirmed, although it will be no earlier than 29 March 2017 and no later than the date of the UK's official withdrawal from the EU.
Qualifying citizens will be given a grace period of time to apply for documentation proving their settled status post-Brexit. It has not been confirmed how long this grace period will be, but it is expected to be up to 2 years from the date the UK officially leaves the EU.
The form of application, and the application process, has not yet been confirmed. The government have indicated that they intend to offer a streamlined digital process which will allow the use of government data (such as income records) to minimise the burden of the documentary evidence required.
EU citizens who currently live in the UK, but who will not have accrued 5 years' continuous residence by the date the UK officially exits the EU, will be able to apply for temporary status in order to remain in the UK until they have accumulated 5 years' residence.
This temporary status will not necessarily be available to those who have arrived in the UK after the "specified date". This specified date has not been confirmed, but it will be no earlier than 29 March 2017.
The position therefore remains uncertain for EU nationals who moved to the UK more recently, and we await further information from the government on this point.
Although UK Registration Certificates, Residence Cards and Certificates of Permanent Residence will not be valid post-Brexit, the government have suggested that individuals who hold Certificates of Permanent Residence may benefit from a more streamlined process of obtaining the required documents after Brexit. Pre-emptive applications made prior to Brexit therefore may not be in vain.
Furthermore, EU citizens who acquire British Citizenship prior to Brexit should not need to apply for any additional documentation to confirm their residence rights in the UK after the UK has left the EU.
Individuals who have applied, or are in the process of applying, for a Certificate of Permanent Residence may therefore consider applying for British Citizenship to avoid needing to make additional applications post-Brexit.