A Brexit deal was announced by the European Union and the UK government on 24 December 2020, this deal provides guidance on what it means for UK/EU Social Security interaction.

Below is a summary of the current position:

  • The transitional arrangement in The Withdrawal Agreement covers assignments that began in 2020 and carry on uninterrupted.
  • From 1 January 2021 new rules apply to assignments that start after that date:
    • Each EU country has the option to opt-in or out of detached worker rules which effectively mimic the old posted worker rules. If the country opts in then the detached worker rules apply to assignments of up to two years to those countries from the UK and vice versa. If the country opts out the individual is required to pay Social Security in the country in which they are physically working unless their secondment started prior to that country opting out
    • There are new multi-state worker rules that apply which are very similar to the old rules.

HMRC have confirmed that Austria, Hungary, Portugal and Sweden have opted in to the detached workers rules. This means that assignments starting from 1 January 2021 will be able to be covered by a Certificate of Coverage such that the individual can remain paying Social Security in their home country for up to two years.

There is no provision for extending this period in the detached worker rules as is the case under the EEA posted worker regulations. Importantly the new Detached Worker rules do not cover Norway, Iceland, Liechtenstein and Switzerland which are covered by rules and agreements specific to those countries.


The full guidance can be found on HMRC’s website at www.gov.uk.

For employers with globally mobile employees in Europe, clarity on the rules is an important step towards identifying risk and next steps. As countries that opt-out are identified, employers should quantify the potential employer and employee social tax costs for assignees and employees with commuter arrangements.

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To find out how specialists from across our network of member firms can help you align a global mobility strategy with business objectives, contact one of the global mobility contacts listed in our expatriate tax guide or speak to your local member firm.