Produced by Tolley in association with Jim Yuill at The Yuill Consultancy
  • 14 Oct 2021 17:01

The following Employment Tax guidance note Produced by Tolley in association with Jim Yuill at The Yuill Consultancy provides comprehensive and up to date tax information covering:

  • EU provisions
  • Background
  • Brexit
  • Short-term assignment from one EU / EEA country to another
  • What is an A1 or equivalent certificate of social security coverage?
  • What if the employee spends longer in the country than expected?
  • Application for A1 or equivalent certificate of UK NIC coverage
  • Validity of the A1 or equivalent certificate
  • Assignment ends early
  • Seconded workers ― longer-term secondment
  • More...

EU provisions


The social security agreement between all EU member states takes the form of EC Regulations which apply across all Member States and also extend by agreement to cover Norway, Iceland, Lichtenstein and Switzerland (referred to in this guidance note as EEA countries).

The UK does not apply these 2004 and 2009 provisions to third country nationals and their contribution positions need to be considered under the previous provisions. The rules are broadly similar.


The UK negotiated a Withdrawal Agreement and left the EU on 31 January 2020 (referred to as ‘exit day’) with an 11-month implementation period up to 31 December 2020. While exit day was important in terms of being the date the UK ceased to be an EU member state, the majority of key domestic tax and social security changes associated with Brexit take effect from the end of the implementation period (specifically, 11pm (GMT) on 31 December 2020, referred to as ‘(implementation period) IP completion day’). See the Brexit ― personal and employment tax implications guidance note.

For NIC purposes, it has been agreed that the option to allow certain employees, seconded from another EEA country or Switzerland to work in the UK, to continue to pay social charges to their ‘home’ country, will continue albeit in a modified form. It is therefore necessary to consider whether the employee was seconded on or before 31 December 2020 (in which case the previous rules apply), or from 1 January 2021 (in which case the modified rules apply).

The rules for those seconded on or after 1 January 2021 are referred to as the ‘detached worker’ rules, and further details are provided below. However, in many cases it may be first necessary for the employee to establish a right to work in the country they are assigned to (eg obtaining any necessary work visa), before confirming which country’s social security system applies.

To see a summary of which country is likely to be obliged to account

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