EU member state markets have grown steadily more integrated over the last decade, and several Western European economies now face persistent labour shortages in specific sectors. As a result, employers across the EU, including Polish companies, increasingly rely on the long-term posting of workers, a mechanism explicitly enabled by EU law.

The rules governing this process sit in Regulation (EC) No 883/2004 and Regulation (EC) No 987/2009 on the coordination of social security systems. A worker sent abroad under this mechanism is called a posted worker (Polish: pracownik delegowany).

What the A1 certificate is and why it matters

The A1 certificate confirms which country’s social security legislation applies to a person temporarily working outside the state where they are normally insured. Its purpose is to prevent double social security contributions, paying into two systems at once, and to guarantee that a person is always covered by exactly one system.

In Poland, A1 certificates are issued by ZUS (the Social Insurance Institution). Since 1 April 2022, applications must be filed exclusively electronically through the PUE/eZUS platform, paper applications are no longer accepted.


– Who can apply for A1
– Classic posting: the 24-month limit
– A1 and remote B2B work: does it apply to you
– Work permits when posting foreign employees
– FAQ

Who can apply for A1

Three categories of applicants can request A1:

  • the employer posting a worker abroad, in practice, it is usually the employer who takes on this obligation;
  • the worker themselves;
  • a sole trader (JDG) who is temporarily moving their business activity abroad.

Applications are filed through ZUS PUE/eZUS on the relevant form, for example US-1 (temporary transfer of a sole trader’s activity to one country), US-34 (occasional remote work abroad, a “workation” scenario) or US-36 (permanent cross-border telework under the 2023 framework agreement, employees only).

Classic posting: the 24-month limit

Under Article 12 of Regulation 883/2004, a worker (or self-employed person) temporarily sent to perform work in another EU state remains subject to the legislation of the sending state, provided that:

  • the anticipated duration of the posting does not exceed 24 months;
  • the person is not sent to replace another posted worker;
  • the employer/sole trader “normally” carries on substantial activity in the sending state (ZUS’s indicative benchmark is roughly 25% of turnover/activity in Poland).

After 24 months, a new posting to the same country generally requires a break of at least two months, during which the activity is again carried out in Poland.

A1 and remote B2B work: does it apply to you

This is the key question for Polish B2B contractors who work remotely for clients based in other EU countries.

If a sole trader (JDG) performs all their work from Poland, without physically travelling to the client’s country, the relevant factor under the lex loci laboris principle (Article 11 of Regulation 883/2004) is where the work is actually performed, not where the client is registered. All activity takes place in a single country, Poland, so there is no cross-border conflict of legislation to resolve, and an A1 certificate is generally not required.

A1 becomes relevant only when the contractor actually performs part of the work abroad, for example:

  • regularly travelling to work on-site at a client’s premises in another EU country (Article 13 applies, work in several states, with an indicative 25% threshold for “substantial activity”);
  • temporarily transferring the entire business to one EU country for up to 24 months (Article 12(2), the same regime as classic posting).

If the contractor relocates permanently to another EU country and works remotely from there for a Polish or foreign client, the Polish JDG effectively stops being the place where the activity is carried out. The legislation of the country of actual residence becomes applicable instead, and ZUS will not issue an A1 in that case.

A foreign client may still ask for an A1 “just in case,” but under Regulation 883/2004 the document is designed for cross-border situations tied to the place of work, not simply for the fact of working with a foreign client.

A separate note for employees (not sole traders): since 2023, the EU Administrative Commission’s “Guidance Note on telework” and a cross-border telework framework agreement (application form US-36) allow an employee to remain insured in the employer’s country if telework performed from their country of residence covers between 25% and 49.9% of total working time. This framework agreement does not cover self-employed persons/sole traders.

Work permits when posting foreign employees

If a Polish company posts a foreign employee (a non-EU citizen) abroad, two documents are mandatory:

  • a valid work authorisation in Poland (zezwolenie na pracę, a standard work permit, or oświadczenie o powierzeniu wykonywania pracy cudzoziemcowi, an employer’s declaration);
  • the A1 certificate from ZUS.
Important: an A1 certificate cannot be issued for a worker who is not legally employed in Poland. Each employee needs an individual A1 and must hold a Polish PESEL number.

This rule applies to all employees of a legally operating Polish company: EU citizens, Polish nationals, and third-country nationals (from Ukraine, India, Belarus, Vietnam, etc.), as long as they are legally employed.

“Other EU member states” in this context also includes EEA states (Norway, Iceland, Liechtenstein) and Switzerland.

FAQ

Do I need A1 even for a trip lasting only a few days? Formally, yes, it is recommended to hold an A1 from day one of working abroad, since it can be requested during an inspection on the very first day.

What happens if ZUS refuses to issue an A1? A refusal takes the form of an administrative decision, which can be appealed in court. A refusal may signal that the legislation of the country where the work is actually performed applies instead.

Is A1 automatically recognised across the whole EU? Yes, under Article 5 of Regulation 987/2009, the document is binding on the institutions of all EU member states until it is withdrawn by the issuing authority.

Bibliography and Legal Basis

  • Regulation (EC) No 883/2004 of the European Parliament and of the Council of 29 April 2004 on the coordination of social security systems, Articles 11-16.
  • Regulation (EC) No 987/2009 laying down the procedure for implementing Regulation 883/2004, Articles 5 and 14.
  • ZUS guidance on forms US-1, US-34, US-36 and the PUE/eZUS platform (zus.pl).
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Author: Moja Firma team.

This article is for informational purposes only and does not constitute legal advice. Every situation depends on the specific contract and individual circumstances. If something about your own situation isn’t quite clear, feel free to book a free consultation with our team.