A Warsaw-based holding company discovered mid-year that its cross-border income flows were being taxed twice – once at source, once in Poland. The structure involved a Polish subsidiary and a foreign parent, but the tax team had overlooked which treaty applied and how Polish domestic law interacted with it. The cost of that oversight ran into six figures.

Poland's network of double tax treaties follows the OECD Model Convention and allocates taxing rights between Poland and partner states across income categories including dividends, interest, royalties, and capital gains. Each treaty sets specific withholding tax rates – often 5%, 10%, or 15% – and defines residency, permanent establishment, and relief methods. Applying the wrong treaty, or misreading residency rules, triggers double taxation and potential penalties under Polish tax law.

This case study traces how one client identified the problem, built a corrective strategy, and extracted lessons that apply to any business with Polish cross-border income. The structure follows four stages: background, strategy, process, and transferable takeaways. Readers with no prior background in Polish tax law will find the argument accessible throughout.

What was the background to the double taxation problem?

The client operated a manufacturing business in the Mazowieckie region. Its parent entity was registered in the Netherlands. For two consecutive tax years, dividend payments from the Polish subsidiary to the Dutch parent were subject to Polish withholding tax at the standard domestic rate of 19%, rather than the reduced treaty rate. The Polish entity's finance team had not confirmed the parent's tax residency status before each payment – a procedural gap that proved expensive.

Under Polish corporate income tax legislation, a payer applying a reduced treaty withholding rate must hold a valid certificate of tax residency from the recipient. Without that certificate, the domestic rate applies automatically. The Polish tax authority, the National Tax Administration (Krajowa Administracja Skarbowa, KAS), treats the absence of a residency certificate as a disqualifying defect – not a correctable technicality. That interpretation forecloses any retroactive rate reduction without a formal refund application.

A secondary issue involved royalty payments for intellectual property licences. The client had classified certain software licence fees as royalties under the domestic definition. The Poland-Netherlands treaty, however, uses a narrower definition. Some payments fell outside the treaty's royalty article entirely, attracting different withholding treatment. This misclassification compounded the withholding exposure. We secured a reversal of a tax surcharge exceeding PLN 800,000 for this manufacturing client in the Mazowieckie region (autumn 2025).

  • Withholding tax applied at 19% instead of the treaty rate of 5%
  • Residency certificates missing for two payment cycles
  • Royalty classification inconsistent with treaty definitions
  • No documented permanent establishment analysis on file

How did the advisory strategy address the treaty gaps?

The strategy had three pillars. First, establish the correct treaty framework. Second, recover overpaid withholding tax through the KAS refund procedure. Third, implement controls to prevent recurrence. Each pillar required separate procedural steps and different timelines. The refund window under Polish tax law is five years from the end of the calendar year in which the overpayment arose – so speed mattered.

On the treaty framework, the team mapped each income category – dividends, interest, royalties, capital gains – against the Poland-Netherlands treaty. That treaty reduces dividend withholding to 5% where the recipient holds at least 10% of the paying company's capital for an uninterrupted 24-month period. Confirming that the Dutch parent met that threshold required a review of the shareholding register and corporate documents going back over two years. The National Court Register (Krajowy Rejestr Sądowy, KRS) records confirmed the shareholding history without ambiguity.

The royalty reclassification required a more granular analysis. Software licences divide into two categories under the treaty: licences for internal business use attract a different rate than licences involving the right to distribute or sublicense. The client's agreements fell predominantly into the internal-use category, which carries a 5% rate under the treaty rather than the domestic 20% rate. (That distinction alone accounted for roughly half the total exposure.) For further context on treaty withholding mechanics in practice, see our analysis of the double tax treaty between Poland and the Netherlands.

What did the recovery process involve?

Filing a withholding tax refund application with KAS requires a specific documentation package. The application must identify the overpayment by tax year, quantify the excess, and attach the recipient's residency certificate valid at the time of each payment. Where a certificate was not obtained at the time of payment, the applicant must provide a retrospective certificate and demonstrate that the recipient was in fact resident in the treaty country throughout the relevant period.

KAS has up to three months to process a refund application, extendable by a further three months if additional verification is required. In practice, applications involving treaty interpretation questions tend to attract extended review. The client's application covered two tax years and four separate payment categories. KAS issued a request for supplementary documents at the six-week mark – standard for cases of this complexity. Our team obtained interim relief protecting the client's cash position for a period of four months while the refund was processed.

The Polish Financial Supervision Authority (Komisja Nadzoru Finansowego, KNF) was not directly involved, but the client's parent entity operated in a regulated sector. That meant the refund timeline had to align with group-level reporting requirements. Coordinating the Polish refund process with the Dutch parent's own tax filings required close communication between advisors in both jurisdictions. Cross-border coordination of this kind is increasingly standard – and the absence of it is a common source of delay. For businesses managing VAT compliance alongside treaty questions, our article on what KSeF means for business in Romania illustrates how Polish digital tax obligations interact with cross-border structures.

What lessons does this case carry for other businesses?

Three lessons emerge clearly. First, treaty benefits are not automatic. Polish tax law places the burden of proof on the payer. A residency certificate must be current, not assumed. Second, income classification under a treaty is not the same as classification under domestic law. The two frameworks use different definitions, and the gap between them creates real exposure. Third, the five-year refund window is generous – but it closes. Businesses that identify overpayments late lose recovery options that would otherwise be available.

Transfer pricing is a related risk that this case did not directly engage, but it sits alongside treaty analysis in any cross-border structure review. Where related-party payments – including those for IP licences – are not priced at arm's length, KAS can challenge both the amount and the classification. That dual exposure makes periodic documentation reviews essential. For businesses holding IP in Poland and considering the IP Box regime, the interaction between IP Box benefits and treaty withholding rates deserves specific attention from a qualified tax advisor Warsaw-based or otherwise. Property-holding structures face analogous complexity; our discussion of real estate tax reclassification disputes illustrates how classification errors compound over time.

What to prepare before a treaty compliance review:

  • Valid residency certificates for all foreign payees, renewed annually
  • Contractual classification of each payment type against the applicable treaty article
  • Shareholding register records confirming ownership thresholds and holding periods
  • Transfer pricing documentation for all related-party cross-border payments
  • Internal timeline mapping treaty refund windows against open tax years

We also secured a reduction of assessed withholding tax interest exceeding PLN 120,000 for an IT sector client in Lower Silesia (spring 2026), by demonstrating that the original classification error arose from a genuine treaty ambiguity rather than negligence. That outcome required detailed written submissions to KAS and a formal interpretive ruling request. The process took five months – which is why early identification of treaty mismatches matters more than any single procedural step.

Specific situations require individual analysis. Applying a treaty incorrectly – or failing to apply it at all – can produce tax costs that are difficult to reverse and, beyond the refund window, impossible to recover. The irreversible nature of that exposure makes early-stage treaty review one of the highest-return compliance investments a cross-border business can make.

To discuss how Polish double tax treaty provisions apply to your specific structure, contact info@kordeckipartners.com.

Frequently asked questions

Q: How long does a withholding tax refund application take with KAS?

A: The standard processing period is three months from the date the application is filed. KAS may extend this by a further three months if additional verification is required. Applications involving treaty interpretation questions or multiple tax years routinely attract the extended timeline. Filing a complete documentation package from the outset reduces the risk of supplementary information requests that delay the process further.

Q: Is it a common misconception that treaty rates apply automatically without documentation?

A: Yes. Many payers assume that once a treaty exists between Poland and the recipient's country, the reduced rate applies by default. Polish tax law requires the payer to hold a valid residency certificate at the time of payment. Without it, the domestic rate applies. Obtaining certificates retroactively supports a refund application but does not eliminate the original withholding obligation or associated interest exposure.

Q: Does the family foundation structure in Poland affect treaty withholding analysis?

A: A Polish family foundation (fundacja rodzinna) is treated as a separate legal entity for tax purposes. Where a family foundation receives income from a foreign source, or where a foreign entity pays income to a foundation, the applicable treaty depends on the foundation's own tax residency status. The interaction between Polish family foundation rules and treaty provisions is a developing area of Polish tax law that warrants specific advice before structuring payments.

About KORDECKI & Partners

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 cross-border tax structuring, treaty compliance, and KSeF implementation. 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.