If you are a UK employer, with employees working in the EU, EEA or Switzerland, the country in which social security contributions are paid on their salary and benefits is currently set by EU Social Security Coordination rules.
The purpose of the EU rules is to ensure that employees and employers are only subject to the social security regime of a single member state at any one time, so there can be no double charges on the same income.
The starting point is that contributions should be paid where the work is done, regardless of where in the EU (EEA or Switzerland) the employer is based. However, there are special rules for individuals who work outside their home country for temporary periods and for individuals who work in more than one country at the same time.
Broadly this means that:
- If you employ workers to work for you in an EU, EEA country or Switzerland, you (and they) must pay social security contributions in the country where the work is done.
- If you employ workers to work for you in more than one EU, EEA country or Switzerland at the same time, you (and they) must pay social security contributions in the country in which they live, provided they carry out a "substantial amount of activity there". There are special rules to decide this.
- If you second or post UK workers temporarily to work for you in an EU, EEA country or Switzerland, you (and they) continue to pay UK social security contributions provided certain conditions relating to the assignment are met (the Posted Worker rules). In these circumstances, neither you nor they pay social security contributions in the country where the work is performed.