A Kraków-based distribution company with 14 subsidiaries across Poland received a letter from its accounting software provider in late 2025. The message was blunt: the National e-Invoice System (Krajowy System e-Faktur, KSeF) would become mandatory for all VAT-registered businesses. The company had three months to integrate its ERP system, train its finance team, and restructure its invoicing workflows. None of those tasks were small.

KSeF is Poland's centralised platform for issuing and receiving structured electronic invoices. From 1 February 2026, the obligation applies to all active VAT taxpayers in Poland, with penalties for non-compliance reaching PLN 100% of the VAT shown on a non-compliant invoice. The system is operated under the supervision of the National Revenue Administration (Krajowa Administracja Skarbowa, KAS) and requires every B2B invoice to be assigned a unique KSeF identifier before it is treated as legally valid.

This case study traces how the Kraków distributor moved from initial confusion to full compliance. It covers the background, the strategy our team recommended, the implementation process, and the lessons that apply to any business operating in Poland – whether a domestic manufacturer, a foreign-owned subsidiary, or an IT services provider.

What was the business facing?

The company issued roughly 4,000 invoices per month across its group. Each subsidiary used a slightly different invoicing template. Some used external accounting firms; others maintained in-house finance teams. None of the systems were connected to the National Court Register (Krajowy Rejestr Sądowy, KRS) or to KAS in any automated way. The complexity was real.

Polish tax law now requires that structured invoices carry specific XML fields – buyer and seller tax identification numbers, invoice date, net value, VAT rate, and a KSeF reference number. A missing or incorrect field causes the invoice to be rejected by the system. A rejected invoice cannot be corrected simply by reissuing it; the entire submission sequence must restart. For a business processing thousands of documents monthly, each rejection carries a direct cash-flow cost.

The Polish Financial Supervision Authority (Komisja Nadzoru Finansowego, KNF) plays no direct role in KSeF, but the company's CFO was concerned about downstream effects on its financing arrangements. Banks in Poland had begun asking borrowers to confirm KSeF readiness as part of credit covenant reviews. Non-compliance was not just a tax risk – it was a financing risk.

  • 14 legal entities, each needing separate KSeF credentials
  • Four different ERP systems across the group
  • Two subsidiaries using external accounting firms with no API integration
  • One subsidiary with significant cross-border sales requiring analysis under the double tax treaty between Poland and the Netherlands

How did we structure the compliance strategy?

Our tax practice recommended a phased approach. The first phase – lasting 30 days – focused on entity mapping and credential registration. Each subsidiary needed its own KSeF token, issued through the KAS taxpayer portal. Tokens are tied to the NIP (Polish tax identification number) of each entity, not to the group as a whole. This is a point many multi-entity groups miss initially.

We obtained interim KSeF credentials for all 14 entities within 18 business days. The two subsidiaries using external accountants required written authorisation documents granting those firms the right to issue invoices on the entity's behalf. Polish tax law distinguishes between "self-invoicing" and "third-party invoicing" modes within KSeF, and the authorisation forms differ. Using the wrong form causes a system-level rejection that cannot be reversed without re-filing.

We secured a clean credential set for a logistics subsidiary in Małopolska by autumn 2025, avoiding a gap in invoicing capacity that would have delayed payment collection by at least 30 days. That outcome mattered directly to the group's working capital position.

The second phase covered ERP integration. Three of the four systems had vendor-supplied KSeF connectors available. The fourth required custom API development. We coordinated with the IT team and the software vendor to define the minimum required XML schema fields, reducing the development scope and cutting the integration timeline from an estimated 12 weeks to 7 weeks.

What does the process look like in practice?

Once credentials were in place and ERP connectors were live, the operational process followed a clear sequence. The finance team issues a draft invoice in the ERP. The system converts it to the required FA(2) XML schema. The file is submitted to KSeF via API. KSeF assigns a unique reference number (the "KSeF number") within seconds during business hours. The invoice is then sent to the buyer – but only after the KSeF number is attached. Sending before assignment is non-compliant.

Buyers receiving invoices must also be registered to accept structured documents. For domestic B2B transactions, this is automatic for VAT-registered entities. For buyers who are not VAT-registered – including some foreign entities – different rules apply. The company's cross-border sales required a separate analysis, particularly for Dutch counterparties. Questions about treaty interaction and VAT treatment were addressed through the framework discussed in the double tax treaty between Poland and the Netherlands guide.

Correction invoices (faktury korygujące) follow the same submission path but require the original KSeF number as a reference field. The company had historically issued a high volume of corrections – roughly 8% of total invoices. Reducing that rate was identified as a secondary compliance goal, since each correction now creates a visible audit trail in the KAS database.

For businesses considering structural changes as part of their KSeF readiness – such as consolidating entities or adjusting their corporate structure – the timeline implications are significant. A liquidation of a subsidiary, for example, triggers its own KSeF deregistration sequence. The process and timeline for liquidation of a sp. z o.o. should be factored into any restructuring plan that touches invoicing entities.

Two subsidiaries also claimed IP Box relief on income derived from proprietary logistics software. The KSeF implementation required those entities to ensure that invoices referencing IP-related services were correctly categorised, since KAS cross-references KSeF data against IP Box declarations during audits.

What are the transferable lessons?

The Kraków group's experience surfaces four practical lessons for any business facing KSeF compliance. First, entity-level registration cannot be delegated upward. Each NIP must be registered separately. A group holding structure does not create a single KSeF account for all subsidiaries. Businesses that discover this late face a gap period during which invoices cannot be issued – with direct revenue consequences.

Second, the correction invoice rate is a KSeF risk indicator. A rate above 5% signals data quality problems in the ERP that will generate audit attention. Reducing corrections before the mandatory date is a compliance investment, not just an operational improvement. Transfer pricing documentation should also be reviewed: KSeF data gives KAS a real-time view of intercompany pricing, and inconsistencies between KSeF invoices and transfer pricing files create examination risk within 90 days of filing.

Third, foreign-owned subsidiaries face an additional layer. A German parent company whose Polish subsidiary issues invoices to EU counterparties must ensure that its local ERP can handle the FA(2) schema without manual intervention. Manual workarounds are not sustainable at scale and are treated as non-compliant if they result in invoices sent before KSeF assignment. Our tax practice in Poland has handled this scenario for clients across multiple jurisdictions.

Fourth, KSeF compliance is not a one-time project. Schema versions are updated by the Ministry of Finance. The FA(2) schema replaced FA(1) with limited transition time. Businesses need a monitoring process – ideally contractually embedded in their ERP maintenance agreements – to ensure that schema updates are applied within the required window, which has historically been 30 days from publication.

The company completed full group-wide KSeF compliance before the mandatory date. Its correction invoice rate fell from 8% to under 3% as a secondary benefit of the data quality work. The financing covenant review passed without issue.

Frequently asked questions

Q: Does KSeF apply to foreign companies selling to Polish buyers?

A: Foreign companies not registered for VAT in Poland are not subject to the KSeF obligation directly. However, if a foreign entity is VAT-registered in Poland – even without a Polish establishment – it falls within the mandatory scope. Any foreign business with a Polish VAT number should review its invoicing workflows against the KSeF requirements before assuming it is exempt.

Q: How long does KSeF credential registration take, and what does it cost?

A: Registration through the KAS taxpayer portal is free of charge and technically straightforward for a single entity. For a multi-entity group, the process involves separate submissions for each NIP and, where third-party accountants are involved, additional authorisation filings. Allowing 15 to 20 business days per entity for the full cycle – including any corrections – is a realistic planning assumption.

Q: Is a family foundation in Poland subject to KSeF obligations?

A: A family foundation (fundacja rodzinna) is a separate legal entity under Polish law and may be subject to KSeF if it conducts activities that make it a VAT taxpayer. Most family foundations operate outside the VAT regime for their core activities, but those that provide services to beneficiaries or engage in commercial transactions should verify their VAT status with a tax advisor before assuming they are outside the KSeF scope.

Specific circumstances in your business require individual analysis. Applying a group-level assumption to each entity – without verifying credentials, schema compatibility, and correction workflows – forfeits the compliance window and creates personal liability risk for management board members responsible for tax obligations.

To discuss how KSeF applies to your Polish operations, email 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 tax compliance, KSeF onboarding, and VAT advisory. 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.