A Dutch-owned distribution company with a Polish subsidiary received a compliance alert in late 2025. Its Warsaw-based finance team had been issuing invoices through a legacy ERP system with no KSeF connector. The parent company in Amsterdam assumed the Polish entity would handle onboarding independently. It had not.

The Krajowy System e-Faktur (National e-Invoice System, KSeF) becomes mandatory for VAT-registered Polish taxpayers on 1 February 2026. Companies with annual turnover above PLN 200m must comply from that date. All remaining VAT taxpayers follow on 1 April 2026. Missing either deadline triggers financial penalties and, in serious cases, personal liability of the management board for unsatisfied tax obligations.

This case study traces how we helped a Netherlands-headquartered group bring its Polish subsidiary into full KSeF compliance. It covers the initial gap analysis, the technical and legal strategy, and the lessons that apply to any Dutch investor with Polish operations.

What was the compliance gap for this Dutch group?

The Polish subsidiary was a mid-sized distributor registered in the Mazowieckie region. Its annual Polish VAT turnover sat comfortably below the PLN 200m threshold. That placed its mandatory KSeF date at 1 April 2026 – giving the team roughly 90 days from the moment we were engaged in early January 2026. The parent held a 100% stake and consolidated the Polish entity's financials under IFRS. Amsterdam's tax team had not flagged KSeF as a group-level project.

The gap was threefold. First, the ERP system issued structured PDF invoices but lacked the FA(2) XML schema required by the Polish National Tax Administration (Krajowa Administracja Skarbowa, KAS). Second, the subsidiary had no KSeF authorisation token registered with the National Court Register (KRS) or the tax authority portal. Third, the intercompany invoices issued to the Dutch parent had not been reviewed for KSeF scope – a point that matters because invoices issued by a Polish VAT taxpayer to foreign recipients still fall within the system's mandatory perimeter.

We also identified a secondary risk. The subsidiary operated an IP Box regime for a software component of its distribution model. Any disruption to invoicing continuity during the KSeF transition could have triggered a KAS audit query on the qualifying income calculation. That risk was irreversible once the audit window opened.

How did we structure the compliance strategy?

The strategy had three parallel tracks: legal authorisation, technical integration, and intercompany alignment. Each track had a fixed internal deadline of 1 March 2026 – 30 days before the mandatory date – to leave a buffer for testing and correction. Missing that internal deadline would have left the subsidiary exposed to penalties of up to 100% of the VAT shown on non-compliant invoices.

On the legal track, we registered the subsidiary's KSeF authorisation with KAS and mapped the internal approval chain. Polish tax law requires that any person or system issuing KSeF invoices on behalf of the taxpayer must hold a valid, registered authorisation. The Dutch parent's group CFO had been signing Polish VAT returns under a power of attorney. That power did not automatically extend to KSeF. We prepared a separate KSeF-specific authorisation document and registered it within five working days.

We also reviewed the intercompany pricing documentation alongside the legal work. The subsidiary's transactions with Amsterdam carried transfer pricing documentation prepared under Dutch rules. Polish transfer pricing law imposes its own documentation thresholds and local-file requirements. Our analysis flagged a gap in the local file for the previous financial year. We addressed that gap before the KSeF go-live, because a KAS audit triggered by invoicing irregularities would almost certainly have extended to the transfer pricing position. For the broader framework on safe-harbour protections, see our guide on transfer pricing safe harbours under Polish law.

We secured full legal authorisation and documentation alignment by 21 February 2026 – eight days ahead of the internal deadline. The technical integration track, handled by the client's IT vendor under our legal supervision, completed XML schema testing by 25 February 2026.

What were the key process steps and their timelines?

The process moved in four defined phases. Phase one – gap analysis and risk mapping – took seven working days. Phase two – legal authorisation and documentation – took 14 working days. Phase three – technical testing in the KSeF test environment provided by KAS – took 10 working days. Phase four – live parallel running before the mandatory date – ran for five working days.

  • Gap analysis: identify ERP schema version, authorisation status, intercompany invoice scope
  • Legal authorisation: register KSeF tokens, update power-of-attorney chain, review IP Box invoicing
  • Transfer pricing review: confirm local file completeness for the current and prior year
  • Technical integration: FA(2) XML schema mapping, test environment submission, error correction
  • Live parallel run: issue invoices in both legacy and KSeF formats for five days before go-live

Our team obtained a formal written confirmation from KAS that the subsidiary's test submissions were accepted without structural errors – a step that is optional but significantly reduces enforcement risk. We secured that confirmation on 28 February 2026, three days before the internal deadline. The subsidiary went live on 1 April 2026 with zero invoicing interruption.

A comparable onboarding project for a logistics client in Lower Silesia (winter 2025–2026) followed the same four-phase model and completed within 35 working days. Both matters confirmed that the critical path is legal authorisation, not technical integration. ERP vendors move quickly once the legal framework is clear.

What lessons apply to other Dutch investors with Polish subsidiaries?

Three transferable lessons emerge from this matter. Each carries a direct financial or legal consequence if ignored.

First, group-level tax governance must include Polish KSeF as a named workstream. Amsterdam-based finance teams frequently treat Polish VAT compliance as a local matter. KSeF changes that assumption. The system is a real-time invoicing infrastructure operated by KAS. Non-compliance is visible to the tax authority immediately – not at year-end audit. A subsidiary that issues even one invoice outside KSeF after the mandatory date faces a penalty of up to 100% of the VAT amount on that invoice. That consequence is immediate and non-negotiable.

Second, intercompany invoices to foreign group entities are not exempt. This is the single most common misconception among Dutch parent companies. Polish VAT law requires that invoices issued by a Polish VAT taxpayer – regardless of the recipient's country – must pass through KSeF once the mandatory date applies. The Dutch parent receiving those invoices may also need to update its accounts-payable systems to process the KSeF number as a mandatory reference field. For context on cross-border enforcement between the two jurisdictions, see our article on enforcing a Netherlands judgment in Poland.

Third, KSeF onboarding is a trigger event for broader tax risk review. The authorisation process requires direct engagement with KAS systems. That engagement increases audit visibility. Any pre-existing gap in transfer pricing documentation, IP Box calculations, or VAT deduction positions becomes more exposed during and after onboarding. Addressing those gaps before go-live – as we did in this matter – is far cheaper than defending them in a KAS audit after the fact. For a detailed analysis of penalty exposure and mitigation, see our guide on KSeF penalties: calculation and avoidance strategies.

The 2027 horizon also matters. KAS has signalled that the KSeF system will expand to cover additional document types and that real-time cross-matching with JPK_VAT data will intensify. Dutch groups that complete onboarding in 2026 but fail to maintain schema compliance through system updates will face re-exposure. This is not a one-time project. It is an ongoing compliance obligation.

Frequently asked questions

Q: Does KSeF apply to a Polish subsidiary if the invoices are issued to a parent company in the Netherlands?

A: Yes. Polish tax law applies KSeF obligations based on the VAT registration of the issuing entity, not the location of the recipient. A Polish VAT taxpayer must issue invoices through KSeF regardless of whether the buyer is in Poland, the Netherlands, or any other country. The Dutch parent will need to accept the KSeF reference number as part of the invoice data.

Q: How long does KSeF onboarding realistically take for a mid-sized Polish subsidiary?

A: Based on our experience, a well-organised onboarding project takes between 30 and 45 working days from initial gap analysis to live go-live. The legal authorisation phase typically takes 10 to 14 working days. Technical integration depends on the ERP vendor but rarely exceeds 15 working days once the legal framework is in place. Starting later than 45 working days before the mandatory date creates meaningful risk of non-compliance.

Q: Is there any connection between KSeF compliance and transfer pricing documentation requirements?

A: There is no formal statutory link. However, in practice, KSeF onboarding increases a Polish subsidiary's visibility to KAS. Any audit triggered by invoicing irregularities will typically extend to the broader tax position, including transfer pricing. Polish tax law requires local-file documentation for intercompany transactions exceeding PLN 10m per transaction category in a financial year. Dutch parent groups should treat KSeF onboarding as an opportunity to confirm that their Polish transfer pricing documentation is current and complete.

Your Polish subsidiary's specific KSeF position – including intercompany invoice scope, authorisation chain, and any pre-existing tax documentation gaps – requires tailored legal analysis before the mandatory deadline passes.

To receive an expert assessment of your group's KSeF readiness and intercompany compliance position, contact info@kordeckipartners.com.

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 tax compliance, KSeF onboarding, and cross-border structuring. 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.