What if I am a multi-state worker?
If you are an individual who works both in the UK and another country within the European Economic Area (EEA), including Switzerland, there are special rules regarding your social security position. The rules apply if you carry out more than 5% of your work in a second country.
These ‘multi-state workers’ normally pay National Insurance contributions (NIC) or social security contributions in the country that they are resident in, provided that they also perform ‘substantial’ duties in that country.
“Residence” is defined for social security purposes as the place where a person habitually resides, that is the place where the employee has the strongest personal connections.
“Substantial” is defined as being no less than 25% of working time and/or remuneration. So, if an employee is working in both the UK and also in their home country, they will still be insured in the home country rather than in the UK, so long as they spend at least 25% of their working time there and keep the relevant social and economic ties.
Where the employee is not performing a substantial part of his activities within his home member state (state of residence), the position is generally that he pays into the social security system of the member state where his employer has its “registered office or place of business”.
If you are unsure where you should pay social security, HMRC may be able to help determine the position. There is a form that you can complete to send to HMRC, on the GOV.UK website.
There is also further information on the EU website.
You can find a list of the EEA countries on our page EU and EEA countries.