Multi-state workers, Assignments and Brexit. How is Swiss Social Security impacted? - Tax Blog

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The UK’s departure from the EU means that EU regulations no longer apply in UK/Swiss cross-border social security cases. While the governing principle for EU cross-border cases is payment into a single system, Brexit will mean that Swiss and UK nationals who work in both countries will need to pay split contributions. All third country nationals might even risk having to pay double contributions.

To mitigate this, employers should apply now for extensions of the multi-state worker certificates of coverage (A1).


The United Kingdom left the European Union on 31 January 2020 (Brexit), which marked the beginning of a transition period. With the conclusion of a transitional agreement on 31 October 2019, the same treatment as per the Agreement on the Free Movement of Persons in the area of social security was guaranteed and the existing rules continue to be applied until 31 December 2020.

To date, no agreement on the future relationship between the EU/Switzerland and the UK has been concluded. Consequently, the coordination of international social security for new cross-border situations (initiated after 31 December 2020) between the UK and Switzerland remains unclear.

If no agreement can be reached, the 1968 Convention on Social Security between Switzerland and the United Kingdom (this agreement between the UK and Switzerland has remained as part of Swiss and UK law despite its limited scope) will again apply fully as of 1 January 2021.

As this is the most likely scenario, at this point it makes sense to take stock now and to analyse if any actions are needed before the year ends.

A. Assignments from Switzerland to the UK and vice versa before and after Brexit

New assignments before 31 December 2020 and ongoing assignments

For assignments which began before 31 December 2020 a European format certificate of coverage (A1) can be applied for, which will ensure the individual will remain in the Social Security System of the home country for the duration of the assignment.

New assignments after 1 January 2021

In situations where the assignment starts on 1 January 2021 or later, the 1968 Swiss/UK totalisation agreement will apply. This agreement has provisions to allow assignees to remain in their home social security system without restrictions with regard to citizenship. Hence, for those individuals (Swiss and UK citizens but also third country nationals) the situation does not change significantly. A UK / Swiss certificate of coverage can be applied for in those cases.

Deloitte’s view:

For ongoing assignments, we suggest checking when the A1 expires. In case the assignment is due to continue beyond this point it might make sense to apply for an extension this year to ensure continuity.

B. Multi-state workers between Switzerland and the UK before and after Brexit

Ongoing activities and new multi-state worker activities before 31 December 2020

Individuals who work in at least two countries (multi-state workers) and who started working in this pattern prior to 31 December can rely on their existing A1 as any A1 certificates issued before the year-end will remain valid.

New multi-state worker activities after 1 January 2021

For multi-state worker activities initiated as of 1 January, the situation gets more complicated, since there is no multi-state worker clause in the 1968 Swiss/UK totalisation agreement which is only applicable to Swiss and UK citizens in this regard.

For Swiss and UK multi-state workers this will result in a split payment of social security contributions based on income generated in each country.
For any other third country nationals this could lead to double payment of social security contributions. Such situations might need to be mitigated by a change to the treaty or issuance of a memorandum of understanding.

Deloitte's view: 

We understand it is the intention of the federal authorities to agree on a new totalisation agreement with the UK that also covers the situation of multi-state workers including third country nationals.

Until then, for on-going multi-state worker activities, it therefore makes sense to apply for an extension of the A1 now. Generally, an A1 for multi-state workers can be granted for a maximum duration of 5 years before the situation needs to be re-evaluated. However, the Swiss social security authorities are free to choose any period between one and five years. Therefore, the length of the possible extension will differ between authorities.

If you would like to discuss more on this topic, please do reach out to our key contacts below.

Find our more about International Social Security and our solutions. 

Key contacts


David Wigersma - Partner, Global Employer Services

David has 17 years of experience in the area of international corporate and individual taxation planning. He specialises in addressing the complex compliance needs of a cross-border workforce with varied elements of compensation.


Tabea Nyfeler_110x110

Tabea Nyfeler - Senior Manager, Global Employer Services

Tabea is a recognized expert in the fields of international tax and social security planning. She is the co-lead of our international social security team in Switzerland. Over her career, she has acquired experience in a number of other areas of reward and mobility, including : global employment taxes, rewards, equity based compensation and pensions. Moreover, she has considerable experience in managing global mobility projects for multinational companies across a broad range of industries. Tabea is a Certified Tax Advisor and has authored publications on international tax and social security law.


Harry Verougstraete - Senior Manager, Global Employer Services 

Harry is a Senior Manager within the Global Employer Services team of Deloitte in Switzerland. He is leading our Posted Workers Directive (PWD) offering and is co-leading our international social security team in Switzerland. Harry has more than 9 years of experience with Deloitte Belgium and Switzerland. He supports companies on global mobility related matters and is specialised in coordinating global mobility programs. He advices on tax, social security and PWD related matters. 


Pernilla Siggberg_110x110

Pernilla Siggberg - Consultant, Global Employer Services 

Pernilla is a consultant within Deloitte’s Global Employer Services. In that role, she supports clients with a variety of topics within international expatriate taxation and social security to ensure compliance amongst their mobile workforce. Pernilla holds a Bachelor of Laws degree from the Abo Akademi University in Turku, Finland and a Master’s degree in Management and Law from the Zurich University of Applied Sciences. Pernilla is fluent in several languages, including English, German, Swedish and Finnish. Prior to joining Deloitte in October 2018, she worked as a research associate within international business at a university.



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