Contributions · Social security (ZUS) and health insurance

Posting and the A1 certificate — where a foreigner's contributions are paid

Published: 10 August 2026 · Author: Dariusz Włodarczyk Kancelaria TRC · Reading time: approx. 7 min

In cross-border work, the key question is which country's legislation applies to the employee. We explain the single-legislation principle, the role of the A1 certificate and the rules on posting within the EU.

Table of contents
  1. Coordination of systems in the EU
  2. A1 certificate
  3. And third-country nationals
  4. Risk of not having an A1
  5. Legal basis and sources

1. Coordination of systems in the EU

In the European Union, the EEA and Switzerland, coordination of social security systems applies (Regulations 883/2004 and 987/2009). The basic rule: a person is subject to the legislation of one country — as a rule, the country where they work.

2. A1 certificate

A1 is a certificate confirming which country's social security legislation applies to a given person. When an employee is posted, it allows insurance to be maintained in the sending country.

Posting: in a typical posting within the EU, an employee may as a rule remain insured in the sending country for up to 24 months — on the basis of an A1.

3. And what about third-country nationals

The coordination rules may also cover legally employed third-country nationals moving within the EU — provided the conditions are met. Each situation should be assessed individually, as it depends on status and on the posting route.

4. Risk of not having an A1

Risk: the absence of a valid A1 during a posting may lead to the place of contribution being challenged and contributions being demanded. Obtain the document before work abroad begins.
Show more: how to obtain an A1 certificate
The rules on coordination and on the coverage of income of EU/EEA workers by contributions are discussed in more detail in: I. Gęsicka, P. Majka, M. Rydzewska, J. Wantoch-Rekowski, Zatrudnianie cudzoziemców. Problematyka prawa pracy, administracyjnego i finansów publicznych, Wolters Kluwer, Warsaw 2026.

How to obtain an A1

The A1 is issued on request by the competent institution (in Poland — ZUS). It is worth applying in advance and carrying it while working abroad, as it is often checked by the institutions there.

Posting workers? We will ensure the right insurance

We will determine the applicable legislation, help obtain an A1 and avoid double contributions in cross-border work.

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Legal notice: this article is for information purposes only and does not constitute legal advice. Legal status: 2026 (EU Regulations 883/2004 and 987/2009 on the coordination of social security systems).

Sources: EU Regulations 883/2004 and 987/2009; zus.pl — coordination. The above commentary is our own; the provisions cited should be verified against the current text of the act before taking any action.