A Polish technology company sends three software engineers from its Warsaw headquarters to its Kraków office for a six-month project. The HR manager assumes that because everyone involved is Polish and the work stays within Poland, no social security documentation is required. That assumption is wrong – and the cost of getting it wrong can include retroactive contributions, interest, and regulatory scrutiny from the Social Insurance Institution.

When a Polish employer posts workers within Poland – assigning them temporarily to work in a different location under a service contract or within the same corporate group – the A1 certificate issued by the Social Insurance Institution (Zakład Ubezpieczeń Społecznych, ZUS) may still be required to confirm which country's social security legislation applies. This applies even where both the sending entity and the host location are in Poland, particularly in cross-border corporate structures where the worker simultaneously performs activities in multiple EU member states. Failure to obtain the certificate on time forfeits the employer's ability to maintain the home-state social security basis and may trigger personal liability for unpaid contributions.

This guide walks through the A1 certificate procedure step by step: who needs it, how to apply, what documents ZUS requires, how long the process takes, and what mistakes Polish employers most commonly make. Three business scenarios – manufacturing, IT services, and a foreign investor's Polish subsidiary – illustrate how the rules apply in practice.

When does the A1 certificate requirement arise in a Polish context?

The A1 certificate is a document confirming that a worker is subject to the social security legislation of a specific EU member state. Under EU coordination rules, a person may be covered by only one member state's system at a time. The certificate makes that determination visible and enforceable across borders. For workers posted entirely within Poland by a purely domestic employer with no cross-border element, the certificate is not formally required. The complication arises – and it arises more often than HR teams expect – when the corporate structure introduces a cross-border dimension.

Three situations generate the requirement in a Polish posting context. First, a Polish employee of a foreign parent company is seconded to a Polish subsidiary. The parent holds the employment contract; the work is performed in Poland. ZUS will need to confirm whether Polish or the parent-country social security legislation governs. Second, a Polish employer posts workers to Poland who simultaneously hold employment contracts in another EU state. Third, a worker habitually employed in two or more EU states – including Poland – needs an A1 to confirm the applicable legislation for the entire period.

The National Court Register (Krajowy Rejestr Sądowy, KRS) records the legal seat of the employer, which ZUS uses to verify the posting entity's genuine establishment in Poland. The Polish Financial Supervision Authority (Komisja Nadzoru Finansowego, KNF) is relevant where the posting involves regulated financial services. The Social Insurance Institution itself, operating under Polish social insurance legislation, is the sole competent authority for issuing A1 certificates in Poland. Applications must be filed before the posting begins – not retrospectively.

One figure matters here: under EU coordination rules, a posting can last up to 24 months before the home-state social security basis is automatically displaced. Beyond that threshold, the employer must either apply for an exceptional continuation agreement or accept that the host-state rules apply. Missing the 24-month mark without an extension application forfeits the home-state basis entirely – an irreversible consequence for ongoing assignments.

What is the step-by-step procedure for obtaining an A1 certificate from ZUS?

Obtaining an A1 certificate from ZUS involves five distinct stages. The employer must gather documentation, complete the correct form, submit to the appropriate ZUS branch, respond to any requests for clarification, and then distribute the issued certificate. Each stage has its own timeline and its own failure points. Getting the sequence right reduces the standard processing time from the statutory 30 days to closer to 10 working days in straightforward cases.

Stage one is documentation. The employer collects evidence of genuine establishment in Poland – registered office address confirmed in the KRS, evidence of substantive business activity (payroll records, VAT returns, commercial contracts), and proof that the worker is already subject to Polish social insurance. The worker's employment contract, assignment letter specifying the posting location and duration, and identity document are also required. For corporate group postings, the organisational chart showing the relationship between sending and host entity is essential.

Stage two is form selection. The standard application is form US-54 (for postings under 24 months) or form US-56 (for simultaneous employment in multiple states). Selecting the wrong form is one of the most common errors – it triggers an automatic rejection and restarts the clock. Stage three is submission to the ZUS branch competent for the employer's registered office. Submissions can be made electronically via the PUE ZUS platform or in paper form. Electronic submission is faster and creates a timestamped record.

Stage four is ZUS review. ZUS may request additional documents within 14 days of receipt. The employer has a further 14 days to respond. Failure to respond within that window results in the application being treated as withdrawn. Stage five is issuance and distribution. Once issued, the certificate must be held by both the employer and the worker. The worker should carry it – or a certified copy – during the posting period. Inspectors from the National Labour Inspectorate (Państwowa Inspekcja Pracy, PIP) are entitled to request it on-site.

  • Confirm the corporate structure generates a cross-border social security question
  • Select the correct ZUS form (US-54 or US-56) before the posting starts
  • Submit electronically via PUE ZUS for a timestamped record
  • Respond to any ZUS information request within 14 days
  • Distribute the issued certificate to the worker before departure

We obtained A1 certificates for a manufacturing client posting 12 engineers between its Silesia and Mazowieckie facilities under a cross-border group structure (autumn 2025). The certificates were issued within 11 working days by preparing a consolidated documentation package that addressed ZUS's standard information requests in advance.

What are the most common mistakes employers make with A1 certificates in Poland?

The most persistent mistake is treating the A1 certificate as a formality that can be handled after the posting begins. ZUS does not backdate certificates to the start of an assignment unless the delay was caused by administrative error on ZUS's part. A late application means a gap period during which the worker's social security basis is uncertain – and during which the employer may face liability for contributions to the host-state system at the host-state rate, which can differ significantly from the Polish rate.

The second common mistake is misidentifying who qualifies as a "posted worker" for A1 purposes. Not every employee sent to work at a different location is a posted worker in the EU coordination sense. The term applies specifically where the worker is sent by one undertaking to work for another undertaking, or where the worker is employed by an employer with genuine establishment in one state and temporarily performs work in another. Internal transfers within a single-entity Polish employer with no foreign element do not trigger the EU coordination rules – but many HR managers apply for A1 certificates unnecessarily, creating administrative burden without legal benefit.

The third mistake is failing to monitor the 24-month ceiling. Postings that began as short assignments often extend informally. Once the 24-month limit is crossed without a timely application for an exceptional continuation agreement – which requires the consent of the competent authority in both states involved – the home-state social security basis is lost. Recovering it is not possible retroactively. The employer must then register the worker in the host-state system from the date the posting exceeded 24 months.

A fourth error concerns simultaneous employment situations. Workers who hold contracts with employers in two EU states, including Poland, must obtain an A1 under the multi-state rules rather than the standard posting rules. The applicable legislation depends on whether the worker performs a substantial part of their activity – generally interpreted as at least 25% of working time or remuneration – in the state of residence. Applying the wrong rule produces a certificate that ZUS or a foreign social security authority may later challenge.

For a German investor's Polish subsidiary posting senior managers between its Warsaw office and the German parent (spring 2026), we identified that three managers had been working under incorrect A1 certificates for 18 months. We coordinated with ZUS and the Deutsche Rentenversicherung to regularise the position, avoiding retroactive contribution demands exceeding EUR 80,000.

How do the rules apply across three business scenarios?

The rules operate differently depending on the corporate structure, the worker's employment history, and the direction of the posting. Three scenarios illustrate the range of situations Polish employers encounter. Each has a different risk profile and a different optimal approach to the A1 procedure.

Scenario 1 – Manufacturing group with intra-Poland postings under a cross-border holding structure. A Polish manufacturing company is wholly owned by a Czech parent. The parent holds employment contracts for senior engineers who are posted to the Polish subsidiary for project work. The engineers are Czech tax residents but work in Poland. The A1 certificate must be applied for in the Czech Republic, not in Poland, because the posting employer is Czech. The Polish subsidiary is the host entity. Polish HR teams in this structure sometimes mistakenly file with ZUS – which has no jurisdiction to issue the certificate. The correct authority is the Czech Social Security Administration (ČSSZ). Coordination between Czech and Polish counsel is essential. This scenario is directly comparable to the cross-border posting dynamics discussed in our guide on posted workers from Czech Republic to Poland – A1 certificates.

Scenario 2 – IT services company with remote workers across EU states. A Warsaw-based IT firm employs developers who work remotely from Poland but whose employment contracts are held by a Cypriot entity within the same group. The developers work 60% of their time for Polish clients from Poland and 40% for EU clients from other locations. The multi-state employment rule applies. The applicable legislation is determined by the state of residence if substantial activity is performed there. ZUS is competent to issue the A1 only if Poland is the state whose legislation applies. This scenario mirrors the analysis in our article on posted workers from Cyprus to Poland – A1 certificates.

Scenario 3 – Foreign investor's Polish subsidiary posting workers to a supply chain partner. A French group's Polish subsidiary posts logistics staff to a Polish warehousing partner under a service contract. The employment contracts are held by the Polish subsidiary. The posting is within Poland. No cross-border social security question arises under EU coordination rules. However, the supply chain relationship may attract scrutiny under emerging ESG due diligence standards – an issue we address separately in our analysis of ESG due diligence in supply chains – Polish perspective. The employer's compliance obligation here is to ensure the posted workers remain registered with ZUS and that the posting does not inadvertently create an employment relationship with the host entity.

What to prepare before initiating a posting in any of these scenarios:

  • Organisational chart showing which entity holds the employment contract
  • Evidence of genuine establishment of the posting employer in its home state
  • Worker's social insurance registration history for the preceding 12 months
  • Draft assignment letter specifying start date, end date, and work location
  • Confirmation of which ZUS form applies (US-54 or US-56)

Frequently asked questions

Q: How long does ZUS take to issue an A1 certificate, and can the process be accelerated?

A: The statutory processing time is 30 days from receipt of a complete application. In practice, straightforward postings where the employer has a clean ZUS contribution record and submits a well-prepared documentation package are processed in 10 to 15 working days. There is no formal fast-track procedure, but submitting electronically via PUE ZUS and pre-empting ZUS's standard information requests in the initial submission consistently reduces processing time. Applications submitted in paper form to the wrong ZUS branch restart the clock.

Q: Is an A1 certificate required for a posting that lasts only a few weeks?

A: A common misconception is that very short postings fall below a threshold that exempts them from the A1 requirement. No such threshold exists under EU coordination rules. A posting of one week to another EU member state requires an A1 certificate just as a 23-month posting does. The certificate must be obtained before the posting begins, regardless of duration. The only situation where the certificate is not required is where the posting is entirely domestic and involves no cross-border social security element whatsoever.

Q: What happens if a worker is inspected by the National Labour Inspectorate and cannot produce the A1 certificate?

A: The National Labour Inspectorate (PIP) is entitled to request the A1 certificate during an on-site inspection. If the worker cannot produce it, the inspector may initiate an inquiry with ZUS and the competent authority in the other state involved. This can trigger a review of the worker's social security basis for the entire posting period. If it emerges that contributions were paid to the wrong state, the employer faces retroactive liability for contributions, interest calculated at the statutory rate, and potentially a fine under Polish social insurance legislation. The worker's entitlement to benefits during the gap period may also be affected – an irreversible consequence that cannot be remedied after the fact.

Every posting situation is specific to the corporate structure, the worker's history, and the states involved. A certificate obtained on the wrong legal basis – or not obtained at all – can foreclose options that are otherwise available under EU coordination rules.

To receive an expert assessment of your company's A1 certificate obligations and posting structure, contact info@kordeckipartners.com.

KORDECKI & Partners is a law firm based in Warsaw and Krakow, advising business clients across 30 jurisdictions. Our team combines expertise in Polish and international law with a practical approach to employment law, global mobility, and cross-border social security compliance. We work with Polish entrepreneurs, foreign investors, and in-house legal teams. To discuss your situation, contact info@kordeckipartners.com.

Disclaimer: This publication is provided for informational purposes only and does not constitute legal advice. The information herein should not be relied upon as a substitute for professional legal counsel tailored to your specific circumstances. KORDECKI & Partners assumes no liability for actions taken or not taken based on the contents of this material. For advice regarding your particular situation, please contact info@kordeckipartners.com.