A Ukrainian IT company seconds three developers to its Polish client for a six-month project. The developers hold valid Ukrainian work permits in Poland. The sending company assumes social security contributions remain in Ukraine. Without an A1 certificate, that assumption is unenforceable – and the Polish Social Insurance Institution (ZUS) may assess contributions retroactively for the entire posting period.
Posted workers from Ukraine to Poland require an A1 certificate to confirm which country's social security legislation applies during the posting. Ukrainian employers posting staff to Poland must obtain the certificate from the relevant Ukrainian social insurance authority before the posting begins. Without a valid A1, Polish social security law applies by default – meaning ZUS contributions become due from day one, often with interest and penalties added retroactively.
This guide explains the A1 procedure step by step: who qualifies, what documents to prepare, how long the process takes, and what mistakes most commonly derail otherwise compliant postings. Three business scenarios – manufacturing, IT services, and a foreign investor structure – illustrate how the rules apply in practice. A checklist and FAQ follow at the end.
What is an A1 certificate and why does it matter for Ukrainian employers?
An A1 certificate is a portable document confirming that a worker remains covered by the social security system of the issuing country during a temporary posting abroad. For Ukrainian employers posting staff to Poland, it serves as the legal basis for continuing contributions in Ukraine rather than switching to the Polish ZUS system. The document is issued by the Social Insurance Fund of Ukraine (Fond sotsialnoho strakhuvannia Ukrainy) or the Pension Fund of Ukraine (Pensiiynyi fond Ukrainy), depending on the contribution type. Without it, Polish law treats the posted worker as locally employed from the first day of work in Poland.
The legal framework rests on the bilateral Agreement on Social Security between Poland and Ukraine, which entered into force and mirrors the posting logic of EU Regulation 883/2004 – without being bound by it. The agreement allows a posting period of up to 24 months under the home-country social security system. Extensions beyond 24 months require a separate exceptional-circumstances agreement between the two competent authorities, which can take several additional months to process.
The practical stakes are significant. A retroactive ZUS assessment covering six months of contributions for three employees can easily exceed PLN 50,000 in principal alone. Interest accrues at 8% per annum. Polish labour inspectors from the National Labour Inspectorate (PIP) now routinely request A1 documents during on-site checks, and ZUS auditors cross-reference posting notifications with certificate records. Missing paperwork forfeits the home-country social security position entirely – an outcome that is difficult to reverse once an audit has begun.
Who qualifies for an A1 certificate under the Poland–Ukraine bilateral agreement?
Not every worker sent from Ukraine to Poland qualifies for an A1. The bilateral agreement sets three core conditions: the worker must be employed by a Ukrainian entity, the Ukrainian employer must carry out substantial activity in Ukraine, and the posting must be temporary. Each condition has practical sub-requirements that determine whether the certificate will be issued at all.
The "substantial activity" test is the most commonly failed. Ukrainian authorities assess whether the sending company genuinely operates in Ukraine – not merely on paper. Indicators include the number of employees based in Ukraine, the volume of contracts performed on Ukrainian territory, and the proportion of turnover generated domestically. A shell entity with no real Ukrainian operations will not receive an A1. This matters particularly for Ukrainian entrepreneurs who have relocated to Poland and try to post themselves back to Polish clients through a nominally Ukrainian company.
The worker must also have been employed by the Ukrainian company for at least one month immediately before the posting begins. That one-month minimum is a hard threshold. Hiring someone in Ukraine on Monday and posting them to Poland on Tuesday disqualifies the arrangement. The posting must replace work the employer would otherwise perform in Ukraine, not simply serve as a mechanism to supply labour to a Polish client on a permanent basis.
Three categories of workers are frequently overlooked in compliance reviews:
- Ukrainian citizens holding a Polish temporary residence permit who are employed by a Ukrainian company and posted back to Poland
- Workers posted to multiple EU countries simultaneously – Poland being one destination among several
- Self-employed Ukrainians who use a Ukrainian sole-trader registration to post themselves
Each category involves additional documentation and, in the multi-country scenario, coordination with the competent institutions of each destination state.
How does the A1 application procedure work – step by step?
The A1 procedure for Ukrainian employers posting workers to Poland involves five sequential steps. The total timeline from document preparation to certificate in hand typically runs 6 to 10 weeks, though backlogs at Ukrainian institutions during wartime conditions have extended some cases to 14 weeks. Starting the process at least two months before the posting date is the single most effective risk-reduction measure available.
Step one is internal eligibility verification. The Ukrainian employer confirms that the worker meets the one-month prior-employment requirement, that the posting duration does not exceed 24 months, and that the company itself passes the substantial-activity test. This internal audit takes three to five working days if records are well-organised.
Step two is document assembly. The core package includes: the employment contract or service agreement, payroll records for the preceding three months, a declaration by the Ukrainian employer confirming the posting terms, and the worker's identification documents. For Ukrainian citizens who also hold Polish documentation (residence card, PESEL number), copies of those documents must be included to allow cross-referencing.
Step three is submission to the competent Ukrainian authority. Depending on the contribution type, the application goes to the Pension Fund of Ukraine or the Social Insurance Fund. Both institutions accept applications in paper form; electronic submission channels exist but are inconsistent in availability due to wartime infrastructure constraints. The statutory processing period is 30 calendar days from receipt of a complete application.
Step four is notification to ZUS. Polish law requires the employer – or the Polish host company acting as the de facto employer – to notify ZUS of the incoming posted worker within 7 days of the posting start date. This notification is separate from the A1 and must be made even while the certificate is still pending. Failure to notify ZUS within 7 days is itself a separate infraction, independent of whether the A1 is eventually obtained.
Step five is document retention. The A1 certificate, the posting notification, and the employment documentation must be kept at the Polish work site or made available electronically throughout the posting period. PIP inspectors may request them at any time with no advance notice required.
We obtained A1 certificates for a Ukrainian logistics company posting drivers across three EU member states, including Poland, coordinating with the Pension Fund of Ukraine and ZUS simultaneously in Mazowieckie region (spring 2025). The process was completed within nine weeks from initial instruction.
What are the three most common mistakes Ukrainian employers make?
Three errors account for the majority of compliance failures seen in practice. Each is avoidable with adequate preparation, but each also carries consequences that cannot be fully undone once an audit or inspection is underway.
The first mistake is treating the A1 as optional when the posting is "short." There is no de minimis exception under the Poland–Ukraine bilateral agreement. A two-week posting carries exactly the same A1 requirement as a 20-month one. The misconception arises from confusion with EU rules, where very short postings in certain sectors have historically received lighter treatment. That logic does not transfer to the bilateral framework. A PIP inspector who finds a Ukrainian worker on a two-week assignment without an A1 will issue a finding regardless of duration.
The second mistake is failing to update the A1 when posting terms change. If the originally notified posting duration is extended, a new or amended certificate is required. Extensions are not automatic. A company that obtains an A1 for three months and then extends the posting to eight months without updating the certificate is unprotected for the additional five months. ZUS can assess contributions for the uncertified period even if the original period was fully compliant.
The third mistake is conflating the A1 with the work permit. These are entirely separate legal instruments. A Ukrainian national working in Poland typically requires a work permit or a declaration of intent to entrust work (depending on the basis of their stay). The A1 addresses social security only. A worker can hold a valid A1 and still be working illegally if the underlying work authorisation is missing or expired. Conversely, a valid work permit does not substitute for an A1. Both must be in order simultaneously.
For companies managing posted workers alongside broader Polish employment compliance, our analysis of employment law compliance for Netherlands companies in Poland covers the overlapping notification and documentation obligations that apply across multiple posting scenarios.
How do the rules apply across three business scenarios?
Abstract rules become clearer when mapped to specific business structures. The three scenarios below cover the most common configurations in which Ukrainian employers post workers to Poland.
Scenario 1 – Manufacturing subcontractor. A Ukrainian metalworks company wins a subcontract from a Polish manufacturer in Silesia. It sends eight welders for four months. The Ukrainian company has 45 employees in Ukraine and derives 80% of its revenue from domestic contracts. It passes the substantial-activity test comfortably. The welders have been employed for over a year. A1 certificates are obtainable. The employer must also register the workers with PIP under the Posted Workers Act (ustawa o delegowaniu pracowników w ramach świadczenia usług) and ensure Polish minimum wage compliance – currently PLN 4,666 gross per month as of January 2026. The A1 and the wage compliance obligation are independent: satisfying one does not satisfy the other.
Scenario 2 – IT services. A Kyiv-based software house seconds two senior developers to a Warsaw fintech client for six months. The developers work remotely from the client's office three days per week and from home two days per week. The remote-work element does not affect the A1 analysis: what matters is that the work is performed in Poland under the direction of the Ukrainian employer. The certificate application proceeds normally. However, if the Polish client begins directing the developers' work – setting tasks, approving outputs, managing schedules – the arrangement may be reclassified as a labour hire, which triggers different legal consequences entirely, including potential personal liability for the Polish client under Polish employment law.
Scenario 3 – Foreign investor structure. A German investor owns both a Ukrainian subsidiary and a Polish operating company. It wants to post Ukrainian engineers to the Polish entity. Because both companies are under common ownership, the posting falls under the "intra-group posting" category. Ukrainian authorities will scrutinise whether the Ukrainian entity genuinely employs the workers or whether the Polish entity is the real employer. The one-month prior-employment requirement applies with particular force here. The German parent should also consider whether the arrangement triggers permanent-establishment risk in Poland for the Ukrainian subsidiary – a separate but connected concern addressed in our guide on cross-border matters involving Poland and Ukraine.
We assisted a German-owned group restructuring the posting arrangements for 14 Ukrainian engineers across its Małopolska facility, resolving a ZUS contribution dispute covering PLN 180,000 in contested assessments (autumn 2024).
What should employers prepare before the first posting begins?
A structured preparation checklist prevents the most common failures. The items below apply to any Ukrainian employer posting workers to Poland, regardless of sector or posting duration.
- Confirm the worker's prior employment in Ukraine meets the one-month minimum and obtain payroll records for the three preceding months
- Verify the Ukrainian company's substantial-activity status – collect domestic contract records, headcount data, and turnover breakdown before submitting to Ukrainian authorities
- Submit the A1 application at least eight weeks before the posting start date, accounting for institutional processing times and potential delays
- File the ZUS posting notification within 7 days of the posting start date, even if the A1 has not yet been received
- Confirm that the worker's Polish work authorisation (work permit, declaration of intent, or temporary protection status) is valid and covers the posting period
Two additional points deserve attention. First, the Polish minimum wage obligation applies to all posted workers from the first day, regardless of what the worker earns in Ukraine. Second, the employer must designate a contact person in Poland who can make employment documents available to PIP or ZUS inspectors at any time. That contact person does not need to be a lawyer, but must have access to the full documentation set.
For employers posting workers to Poland from multiple jurisdictions, our detailed comparison of posted workers from Spain to Poland illustrates how the EU Regulation 883/2004 framework differs from the bilateral-agreement approach applicable to Ukrainian employers – a contrast that matters when managing multi-country posting programmes.
Specific circumstances of each posting require individual assessment. Missing the A1 filing window forfeits the home-country social security position for the entire posting period – a result that cannot be corrected retroactively once ZUS has opened an assessment. To receive an expert assessment of your company's posting structure, contact info@kordeckipartners.com.
Frequently asked questions
Q: Can a Ukrainian worker on temporary protection (UKR status) in Poland also be posted from a Ukrainian employer?
A: Yes, but the two legal regimes are independent. Temporary protection under Polish law grants the right to work without a separate work permit. It does not automatically resolve the social security question. The Ukrainian employer must still obtain an A1 certificate to maintain Ukrainian social security coverage. If no A1 is obtained, ZUS contributions apply in Poland regardless of the worker's temporary protection status.
Q: How long does it take to get an A1 certificate from Ukrainian authorities, and what does it cost?
A: The statutory processing period at the Pension Fund of Ukraine or Social Insurance Fund is 30 calendar days from receipt of a complete application. In practice, wartime conditions have extended some cases to 10 to 14 weeks. There is no state fee for the certificate itself. Legal and administrative costs for preparing the application package typically range from EUR 500 to EUR 1,500 depending on complexity and the number of workers covered.
Q: Is it a misconception that the A1 is only needed for postings longer than three months?
A: Yes, this is one of the most persistent misconceptions in practice. The Poland–Ukraine bilateral agreement contains no minimum-duration threshold. An A1 certificate is required from the first day of any posting, whether it lasts two weeks or two years. The three-month idea likely originates from misreading certain EU Posted Workers Directive administrative simplifications, which do not apply to the bilateral agreement framework governing Ukrainian employers posting to Poland.
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 compliance, posted worker procedures, and cross-border social security matters. We work with Polish entrepreneurs, foreign investors, and in-house legal teams – including through our dedicated Ukrainian and CIS Desks. 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.