Since December 31, 2020, the United Kingdom is not part of the European Union anymore.
As a result, as of January 1, 2021, UK nationals (English, Scottish, Welsh, and Northern Irish) no longer benefit from the freedom of movement to travel within the Schengen area.
As Monaco is member of the Schengen area, Brexit impacts UK nationals who are willing to settle in the Principality of Monaco.
As of January 1, 2021, every United Kingdom citizen over the age of 16 willing to remain for more than three months in Monaco or willing to establish their residence in the Principality must provide the Monegasque Authority with a long-stay visa (type D visa) when applying for a Monaco residence permit. One must apply for such a long-stay visa within the French consulate of their latest domicile.
These rules only apply to United Kingdom citizens making their first application for the Monegasque residency card.
The establishment visa will not be required by the authorities of Monaco for United Kingdom citizens who already hold a valid residence permit, and who are applying to renew it.