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Tax Disputes and Investigations

Comprehensive advice on and represenation within tax disputes and investigations conducted by tax authorities and administrative courts.

Navigating complex tax disputes demands strategic insight. Our team helps businesses resolve controversies with tax authorities efficiently and protect their financial interests.

The tax regulatory environment is becoming increasingly complex, with tax authorities taking a more proactive and assertive approach. CMS advises clients on disputes relating to direct and indirect taxes, tax audits, tax investigations and criminal tax proceedings. We support clients in preventing, managing and resolving tax disputes before tax authorities and administrative courts. Drawing on the strength of the CMS international network, we provide coordinated advice on both domestic and cross‑border tax disputes.

Further reading

Cross‑Border Tax Forecast 2026

Tax Disputes Digest - Summer 2025 Edition

CMS Expert Guide to Transfer Pricing Documentation

Highlighted experience

  • Energy & Infrastructure

    State owned nuclear energy investor

    Representation in a landmark withholding tax dispute linked to the construction of Poland’s first nuclear power plant. Obtained a favourable administrative court ruling setting an important precedent, now pending before the Supreme Administrative Court.

  • Financial Services

    Leading automotive finance group

    Successfully challenged a negative tax ruling concerning the tax neutrality of a merger. The administrative court overturned the ruling, significantly reducing the client’s tax exposure and providing clarity on post‑reform merger taxation rules.

  • Consumer Goods

    International food and nutrition company

    Leading a precedent‑setting VAT dispute on CN classification of flavoured milk products. The case raises systemic questions on reduced VAT rates and may result in a preliminary ruling referral to the Court of Justice of the EU.

  • Banking & Capital Markets

    International private bank

    Advising on a precedent‑defining withholding tax dispute concerning Polish Treasury bond settlements, challenging long‑standing market practice and opening the way for WHT refunds across the financial sector.

  • Financial Services

    Global investment banking group

    Advising on complex tax disputes and overpayment proceedings related to the Polish branch of an international investment bank, including permanent establishment and VAT issues in a multi‑jurisdictional context.

  • Manufacturing

    Polish industrial group

    Advising on tax controversy and criminal fiscal proceedings arising from transfer pricing audits, including defence strategy for management board members and coordination of parallel corporate tax risk assessment.

Awards & Recognitions
01
  • Quote
    "My first choice in Poland for difficult tax structuring tasks.There is always a senior lawyer leading the case and they work efficiently. They are easy to work with, friendly, good listeners and provide the advice which you need, not less or more. I get all my concerns addressed - I really appreciate their agile style of working."
    Legal 500 2026
  • Quote
    "Team was able to quickly join the running project and provide tailored advice on the tax aspects of a complex business model prepared by the parties."
    Legal 500 2026
  • Quote
    "CMS has the courage to engage with both complex and new topics that are highly intellectually demanding. It has the scale and flexibility to build high performing teams."
    Chambers Europe 2026
  • Quote
    "CMS appears to be run seamlessly and without silos. In other words, people within CMS are utilising internal resources and bringing additional support to the process, as required."
    Chambers Europe 2026

Explore more

Events

  • Poland
    28 Apr 2026

    IP Insights webinar series 2026

  • Poland
    02 May 2026

    CMS at INTA 2026

  • Poland
    05 May 2026

    Joint seminar with CMS and Tannenbaum Helpern - A global perspective on securing, maintaining, and enforcing...

  • Poland
    19 May 2026

    HR Horizons 4 – Polish employment law seminar for HR professionals

  • Poland
    28 May 2026

    CMS International Crypto Forum 2026

  • Poland
    30 Jun 2026

    On the Pulse webinar series 2026 - Spring/Summer

Local market knowledge. Global outlook

We provide future-facing legal advice to help your organisation thrive. Combining local market knowledge and a global perspective, and with lawyers in locations worldwide, your organisation benefits from the expertise it needs, even across borders.

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