Within the EU, EEA and Switzerland, a worker should be subject to only one country's social security system at a time. The A1 certificate is the evidence of which one. It is issued by the home country's authority and confirms that contributions continue there while the employee works temporarily elsewhere.
When it is needed
The requirement is broader than many employers assume. It applies not only to long postings but also to short business trips involving work in another member state, including attending meetings or conferences in some interpretations. Labour inspectors in several countries check for it during site visits, and the absence of a valid certificate can result in a penalty and a demand for local contributions.
- Applied for by the employer in the home country, before travel where possible
- Valid for a defined period, with extension possible in some circumstances
- Separate from the right to work; it addresses social security only, not immigration
Why it matters when hiring internationally
A1 is one of the most commonly missed compliance obligations in European business travel, precisely because it feels disproportionate for a two-day trip. It is also directly relevant to the Employer of Record model: the certificate is issued in respect of the legal employer, so the employing entity must be the one to apply. Countries outside this framework use bilateral certificates of coverage under totalization agreements to achieve the same effect.