Following the withdrawal of the United Kingdom from the EU, Regulations (EC) No 883/2004 and (EC) No 987/2009 on the coordination of social security systems, which apply between Switzerland and the EU under the Free Movement of Persons Agreement (FMOPA), will no longer apply between Switzerland and the United Kingdom.
The two states have therefore negotiated an agreement on citizens' rights comparable to the withdrawal agreement agreed between the EU and the United Kingdom. The aim of the agreement in the field of social security is to avoid as far as possible changes for persons currently covered by the FMOPA and to protect the rights acquired under the FMOPA.
The Swiss government has approved the agreement on 19 December 2018. It will apply when the FMOPA is no longer applicable between Switzerland and UK, from 30 March 2019 or from 1 January 2021. This depends on whether or not the United Kingdom and the EU can agree on a withdrawal agreement with a transition period.
You will find here further information on the social security provisions of the agreement via: