A1 Certificates & Social Security
The A1 certificate, explained.
One document decides which country's social security your employee belongs to the moment they work across a border. Miss it, and a one-day trip becomes a compliance problem. Here's what it is — and how Dimmi takes it off your desk.
The Basics
Proof that your employee stays in one social security system.
An A1 certificate — officially the Portable Document A1 — confirms that an employee working temporarily in another EU/EEA country or Switzerland stays covered by their home country's social security, and keeps paying contributions there rather than in the country they're visiting.
It exists because of one simple European rule: a person can only belong to one country's social security system at a time. The A1 is the document that proves which one. It's issued under EU Regulation 883/2004 and covers every branch of social insurance at once — pension, healthcare, unemployment and work-accident cover.
Home country
Social security
A1
Host country
Exempt
One person. One system. At any time.
The Trigger
From the first working day. No exceptions for short trips.
There's no minimum duration and no grace period. The obligation begins the moment the border is crossed and work starts — a one-day conference in Berlin technically needs an A1, just as a six-month posting does.
The line isn't how long. It's whether work happens. A holiday needs nothing. A sales call, a workshop, a client meeting, a research stay — every one of them crosses the line.
A holiday needs nothing. Work of any kind does.
4.6 million A1 certificates were issued across the EU/EEA in 2022 — up 27% in a single year.
Source: European Commission.
Who It Covers
Employees, directors, and the self-employed alike.
Anyone working temporarily across a border inside the EU, Iceland, Liechtenstein, Norway or Switzerland needs an A1 — employees, posted workers, and self-employed people, including managing directors.
Posting (Article 12)
Sent to one country for a defined period. Valid for up to 24 months.
Multi-state work (Article 13)
Regularly working across two or more countries. One certificate, usually renewed each year.
Beyond the EU/EEA — for the US, UK and other countries — the equivalent is a Certificate of Coverage under a bilateral social security agreement. Dimmi handles those too.
Related guide: Posted worker notifications →
The Risk
A missing A1 turns a business trip into a liability.
A1 checks have moved from paperwork to enforcement. Labour inspectors across Europe now ask for the certificate on site — and increasingly in real time.
Without one, the exposure is real: fines reaching several thousand euros per employee in stricter countries, back-payment of social contributions in the host country, project delays and reputational damage — and in some places, workers turned away from the site altogether.
It protects the employee, too. If contributions were paid into the home system, that's where benefits should be drawn. An A1 keeps that record clean across every border.
The Hidden Cost
The certificate is easy. Doing it every time, for everyone, is not.
For a single trip, an A1 is just a form. Across a whole workforce it becomes a moving target: scattered requests, ad-hoc filings through government portals, no single view of who is where, and no warning before a certificate expires.
That's not a legal problem. It's an operational one — and it's where most of the risk actually hides.
The Dimmi Way
A1s prepared, filed, and tracked — without the paperwork on your desk.
Dimmi treats A1 as part of one connected mobility workflow, not a separate chore.
Anticipates
when an A1 is needed, from the trip itself, not after the fact.
Prepares and files
the application and documentation, end to end.
Tracks
every certificate, renewal and expiry in one real-time view across your whole workforce.
Keeps it compliant
with source-linked guidance anchored in current law — no generic outputs, no guesswork.
All of it inside the same secure, EU-hosted platform that runs your immigration and relocations. One partner, one system, every border.
FAQ
Quick answers.
Make A1 compliance effortless and predictable.
From the first business trip to a full posting programme, Dimmi prepares, files, and tracks every certificate — so your team can focus on the work, not the paperwork.