A Spanish-owned subsidiary operating in Poland receives a letter from its Polish accountant in January 2026: KSeF mandatory e-invoicing is live, and the company has no integration in place. The penalties are real. The window to act without disruption is closing fast.

Poland's Krajowy System e-Faktur (National e-Invoicing System, KSeF) became mandatory for large Polish taxpayers on 1 February 2026. Mid-sized and smaller entities – including Polish subsidiaries of Spanish parent companies – face their own hard deadlines through 2026 and into 2027. Missing these thresholds does not simply mean a fine; it precludes the legal validity of invoices issued outside the system, which forfeits input VAT deduction rights for the recipient.

This alert sets out the current deadline structure, identifies which Spanish-linked entities are affected and when, and lists the immediate steps that compliance teams should take now.

What has changed in the KSeF timeline for 2026 and 2027?

Polish tax legislation introduced a phased mandatory KSeF rollout. The Ministerstwo Finansów (Polish Ministry of Finance) revised the original schedule after a technical audit in 2023, pushing the first wave to 1 February 2026. That date is now fixed. Large taxpayers – those whose annual VAT-taxable turnover exceeded PLN 200 million in the prior year – were brought into the system first. From 1 April 2026, the obligation extends to all remaining active VAT payers. Entities that are VAT-exempt face a separate deadline of 1 January 2027.

The change is structural, not procedural. Every B2B invoice issued by a Polish VAT payer must now pass through KSeF and receive a unique numer KSeF (KSeF reference number) before it is treated as legally issued. An invoice sent by email or ERP without that number is not a valid invoice under Polish tax law – regardless of where the parent company is headquartered.

For Spanish groups with Polish operations, this creates a gap that transfer pricing documentation and intercompany billing processes must also address. Intercompany invoices are not exempt. The Krajowa Administracja Skarbowa (Polish National Revenue Administration, KAS) has confirmed that intra-group transactions between Polish entities fall within scope from the same dates.

Which Spanish-linked companies are affected, and when?

The threshold question is simple: does the entity have a Polish tax identification number (NIP) and issue B2B invoices in Poland? If yes, KSeF applies. Three categories matter most for Spanish investors.

  • Polish subsidiaries (spółki zależne): fully in scope from 1 February 2026 if turnover exceeded PLN 200m, otherwise from 1 April 2026.
  • Polish branches of Spanish companies: treated as separate VAT payers – same deadlines apply.
  • VAT-exempt entities: mandatory KSeF from 1 January 2027, but voluntary registration is open now.

One point that surprises Spanish finance directors: a Spanish parent company issuing invoices to its Polish subsidiary for management fees or IP licences is not directly subject to KSeF (it is not a Polish VAT payer). However, the Polish subsidiary receiving those invoices must still process its own outgoing invoices through KSeF. Misaligned billing cycles between Madrid and Warsaw create real cash-flow risk. We resolved a billing-cycle conflict for a manufacturing client in the Mazowieckie region (autumn 2025), where intercompany invoice timing had blocked PLN 1.4m in input VAT claims.

Companies using posted workers from Spain to Poland should also check whether those arrangements generate Polish VAT obligations that trigger KSeF scope earlier than expected.

What should Spanish-linked companies do immediately?

Three actions carry the highest urgency. First, confirm which KSeF deadline applies to your Polish entity – the PLN 200m threshold is based on 2024 turnover reported to the Urząd Skarbowy (Polish Tax Office). If that figure is uncertain, request a formal confirmation from your Polish tax advisor now. The cost of that check is negligible. The cost of missing the deadline is not.

Second, audit your ERP or billing system. KSeF requires structured XML invoices in the FA(2) logical structure. Most Spanish-market ERP configurations are not pre-set for Polish FA(2) output. Integration typically takes 6 to 12 weeks. Companies that started in October 2025 are finishing now. Companies starting in March 2026 are already late for the April deadline.

Third, review intercompany billing flows. Any IP Box arrangements, transfer pricing adjustments, or management-fee structures that generate Polish invoices must be mapped against the KSeF calendar. Our team assisted a technology client in Lower Silesia (winter 2025–2026) in restructuring its IP licensing invoicing chain to align with KSeF requirements, protecting over EUR 800,000 in deductible costs. For background on how Polish safe-harbour rules interact with these flows, see our note on transfer pricing safe harbours under Polish law.

What to prepare before your KSeF go-live date:

  • Confirmation of applicable deadline based on 2024 VAT turnover
  • ERP/billing system compatibility assessment for FA(2) XML format
  • Mapping of all intercompany invoice flows involving Polish entities
  • KSeF access credentials and authorisation structure for finance staff
  • Test invoice submission to the KSeF sandbox environment

Groups with Dutch holding structures above their Polish operations may also find our analysis of the double tax treaty between Poland and the Netherlands relevant when reviewing the full invoice and withholding tax chain.

Specific circumstances of your Polish entity – turnover level, ERP architecture, intercompany billing structure – determine which deadline applies and how much time remains. Delaying this assessment forfeits the preparation window and risks invoice invalidity from day one of the mandatory period.

If your Spanish-linked company has Polish VAT obligations and has not yet confirmed its KSeF readiness, our team will conduct a gap analysis, identify your applicable deadline, and coordinate ERP and documentation alignment: info@kordeckipartners.com.

Frequently asked questions

Q: Does KSeF apply to a Spanish company that only occasionally invoices Polish clients?

A: KSeF applies to entities registered as Polish VAT payers. A Spanish company invoicing Polish clients without a Polish VAT registration is not directly subject to KSeF. However, if that company has a Polish branch or fixed establishment registered for VAT in Poland, KSeF obligations apply from the relevant 2026 deadline. The registration status – not the parent's location – determines scope.

Q: What is the penalty for issuing an invoice outside KSeF after the mandatory deadline?

A: Polish tax law provides for financial penalties of up to 100% of the VAT amount shown on a non-compliant invoice. Beyond the direct fine, an invoice issued outside KSeF after the mandatory date is not legally valid, which means the recipient cannot deduct input VAT. That consequence – loss of deduction rights – is often more damaging than the penalty itself.

Q: Can a family foundation holding Polish real estate be affected by KSeF?

A: A fundacja rodzinna (family foundation) that conducts permitted business activity generating VAT-taxable turnover in Poland may fall within KSeF scope. The key test is whether the foundation is registered as a VAT payer. Most family foundations holding passive real estate assets are VAT-exempt and face the 1 January 2027 deadline rather than the earlier 2026 dates. A tax advisor Warsaw-based or otherwise familiar with Polish tax law should confirm the specific status before that date.

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