In the beginning of November 2020, the Danish Agency for International Recruitment and Integration (SIRI) is sending an information letter to all British citizens residing in Denmark.
The United Kingdom left the EU on 31 January 2020. The Withdrawal Agreement between the EU and the United Kingdom entered into force on 1 February 2020. The purpose of the Withdrawal Agreement is to ensure that British citizens who are legally residing in the EU in accordance with the EU rules on free movement before the end of the transition period (31 December 2020) can continue to reside in the EU also after this date on terms, which overall correspond to the current terms under EU rules of free movement.
All British citizens and their family members residing in Denmark must apply for a new residence document. The issuance of this document is a precondition for maintaining a right to work and reside etc. in Denmark. This also applies to persons with permanent residence rights in Denmark. Existing rights with regard to residence, work etc. are maintained, while the application is being processed. You cannot submit an application for a new residence document before the 1st of January 2021.
You can read more about Brexit at SIRI's website here.
You can also find more information at The Ministry of Immigration and Integration’s website, where the Ministry explains, how Brexit will affect you as a British Citizen living in Denmark. For more information, please take a look at the website here.