Whether there is a withdrawal deal or not, British citizens will require a residency title or other proof of their right of residency in Germany following Brexit.
If there is no deal, as it stands, all British citizens in Germany would have to apply for a residency title by 30 June 2019.
If there is a deal (i.e. the withdrawal agreement between the UK and the EU is ratified), British citizens would still be required to prove their right to residency.
Until the UK leaves the EU, British citizens continue to have the right of freedom of movement. However, some local immigration authorities are introducing a voluntary registration process so that they can contact affected citizens more easily, whatever happens.
For example, the Berlin immigration authority is already inviting UK nationals resident in Berlin to pre-register for a residency permit application. While it is technically voluntary, it is strongly recommended that you register before 29 March 2019 if you are resident in Berlin. The confirmation of registration ensures the residency rights acquired in Germany will remain valid from Brexit until a decision is taken on the subsequent application.
BiG have liaised with the Berlin immigration office and requested clarification on a number of points, including questions from BiG members. These have been addressed through an extensive FAQ page in English and German. Please also read the explanatory notes on the registration page carefully.
If you live outside Berlin please check the website of your local immigration authority for more information on the planned process where you live.