When an employer sends a worker to another EU country for a job, two questions come up straight away: which country's social security applies, and how do you prove it on site? The answer is the A1 certificate for posted workers. This article explains what the A1 proves, the conditions behind it, how it is requested, and what it does not cover.
The A1, officially the Portable Document A1 (PD A1), is a certificate issued by the social security institution of the country whose legislation applies to the worker. For a posted worker, that is normally the home country.
Current EU social-security guidance explains that the PD A1 proves that the worker remains covered by the social security system of the home country while posted to another EU country. In plain terms: contributions keep being paid at home, and the host country should not ask for a second set.
The rules come from EU social security coordination law:
The current consolidated text of both regulations should be checked when planning an assignment.
Article 12(1) requires an employer which "normally carries out its activities" in the sending country. Regulation 987/2009, Article 14(2), explains that this means an employer that ordinarily performs substantial activities there, other than purely internal management activities. A letterbox company that only sends people abroad does not meet this test.
Article 14(1) of Regulation 987/2009 accepts that a worker can be recruited with a view to being posted. The condition is that, immediately before the start of the employment, the person is already subject to the legislation of the Member State where the employer is established.
The anticipated duration must not exceed 24 months. Under the coordination rules, the PD A1 for a posting is issued for a maximum period of 24 months. If the work runs longer, the worker either switches to the host country's system, or the employer asks for an extension. An extension depends on a mutual agreement between the authorities of both countries and must be requested from the issuing authority before the A1 expires.
The worker must not be sent to replace another posted person. Rotating people through the same post to stay under the home system is exactly what this condition blocks.
Under Article 15(1) of Regulation 987/2009, the employer informs the competent institution of the country whose legislation applies, whenever possible in advance. Under Article 19(2), that institution provides an attestation, on request, that its legislation applies, and indicates until what date and under what conditions.
In Romania, the competent institution is the National Public Pension House (Casa Națională de Pensii Publice, CNPP). CNPP issues the portable document A1 and accepts applications through its online services. Other countries have their own institutions, listed on each national social security portal.
A practical sequence for an employer looks like this:
The worker should be able to present the PD A1 during the posting, including during an inspection. While valid, it must be recognised under the applicable coordination rules unless withdrawn or declared invalid by the issuing institution.
This is where many employers get caught. The A1 answers one question only: which country's social security legislation applies. It does not settle the rest.
| Topic | Covered by the A1? | Where the rules come from |
|---|---|---|
| Social security contributions | Yes | Regulations 883/2004 and 987/2009 |
| Pay, working time, leave in the host country | No | Posting of Workers Directive and host country law |
| Posting declaration to the host authorities | No | Host country rules under the Enforcement Directive |
| Income tax | No | National law and tax treaties |
| Healthcare access abroad | No: separate healthcare documents are needed | EHIC for necessary state healthcare during a temporary stay; an S1 may be needed when residence moves |
Two time limits are easy to confuse. The A1 runs up to 24 months for social security. Separately, under the labour law rules, a posting that lasts more than 12 months (18 months after a motivated notification) becomes a long-term posting, and almost all host country employment terms then apply. They are different rules with different clocks. Our step-by-step guide to posting workers in the EU covers the labour law side.
The rules in this article are a general summary of EU law. National procedures, documents and timelines differ, and some situations, such as work in several countries at once or work on board ships, follow other articles of the regulation. Check every case with the competent institution or a qualified adviser.
R.A.M. MULTI INVEST SRL has been based in Constanța since 2013, with its own offices in Constanța and in Hellerup, Denmark. From Constanța, RAM supplies technical personnel for marine and shipbuilding, offshore, oil and gas and solar PV projects. The A1 questions in this article come up whenever an employer based in Romania sends people to work in another EU country.
Who requests the A1 depends on who employs the worker. Under workforce solutions, RAM handles employment, documentation, mobilisation and workforce administration, while the client directs the work on site. RAM's payroll and employment services cover Romania, Denmark and Norway, either as payroll for a client's own employees or as employment through RAM. The employing entity, the assignment terms and any staffing permissions are confirmed for each country and project, and that employer is the one whose name should appear on the A1.
The payroll process RAM publishes follows the same order as the checks above: define the scope (country, headcount, roles, work location and start date), agree the setup (employment model, registrations, duties and terms), onboard the team with contracts and payroll inputs collected securely, then run and review the monthly payroll. RAM also states that payroll support does not remove an employer's registration or legal obligations, and that applies to social security as much as to pay. Before anyone travels, RAM agrees scope, supervision, interfaces and deliverables with the client; the A1 dates and the employer named on it belong in that same conversation.
If you are planning a posting from Constanța, Romania and want to go through the setup, send RAM the project details.
It confirms which country’s social security legislation applies to the worker for the stated period and conditions.
No. Host-country employment terms, income tax and posting declarations are separate matters that require their own checks.
As early as practical before travel. The employer should allow time for review and make the document available during the assignment.
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