KSeF in Poland: what does this mean for your VAT refund?

What is KSeF?

In 2026, Poland introduced a mandatory national e-invoicing system, the Krajowy System e-Faktur, abbreviated KSeF. Through this system, all B2B invoices from Polish VAT-registered companies are centrally registered, validated and archived by the Polish tax authority.

The rollout was phased:

• From 1 February 2026, mandatory for large Polish companies with revenue exceeding PLN 200 million in 2024.
• From 1 April 2026, mandatory for all remaining Polish VAT-registered companies.

A KSeF invoice is a structured XML document in the Polish format FA(3). Upon registration, each invoice is assigned a unique KSeF number issued by the Polish tax authority. This number serves as proof that the invoice has been officially registered and is valid.

Background: why did Poland introduce KSeF?

KSeF is not an administrative requirement that came out of nowhere. Its introduction is an explicit measure by the Polish government to combat VAT fraud and carousel fraud. Poland expects to generate an additional PLN 1.8 billion in annual tax revenue through KSeF, as a result of reduced fraud and unjustified VAT repayments.

KSeF complements other anti-fraud measures Poland had already introduced, such as the split payment mechanism, the system for electronic analysis of financial flows (STIR), and the unified audit file for VAT purposes (JPK).

The European Union granted Poland a special derogation under Article 395 of the VAT Directive to introduce KSeF. This is no coincidence, the European Commission also considers mandatory e-invoicing an effective tool against VAT fraud.

KSeF as part of a European trend

Poland is leading the way with KSeF in Europe, but it is not alone. Through the ViDA legislation (VAT in the Digital Age), adopted on 11 March 2025, the EU has determined that structured e-invoicing and digital reporting will become mandatory for all cross-border intra-EU B2B transactions from 1 July 2030. Belgium, France and Germany are also gradually introducing national e-invoicing requirements.

Poland demonstrates how mandatory e-invoicing works in practice and thereby serves as a blueprint for the broader European implementation.

What does this mean for your VAT refund?

As a foreign transport company reclaiming VAT on costs incurred in Poland, such as fuel, toll charges, hotel stays or vehicle rental, you receive invoices from Polish suppliers. From the implementation dates onwards, these suppliers are required to issue their invoices via KSeF.

This has direct consequences for your refund file:

• Invoice format changes — A valid Polish invoice is now a document registered via KSeF. The supplier generates a PDF from this and sends it to you.
• KSeF number is mandatory — An invoice without a KSeF number from a Polish supplier subject to the requirement is formally invalid for VAT refund purposes.
• Archiving — The KSeF invoice is the authoritative version. Changes cannot be made outside the system.

If you submit invoices for VAT refund that do not meet the KSeF requirements, you risk rejection by the Polish tax authority.

How do you recognise a valid KSeF invoice?

A KSeF invoice can be recognised by a number of standard features. The document carries the designation "E-Faktura / E-Invoice", accompanied by a statement confirming that the invoice was generated from the electronic invoice submitted to KSeF. The invoice also includes a QR code that can be used to verify the authenticity of the issuing party, as well as the KSeF number confirming registration with the Polish tax authority.

Is the KSeF number missing on an invoice from a Polish supplier subject to the requirement? Contact your supplier to obtain the correct KSeF version.

Q2 2026: first full quarter under the new rules

The second quarter of 2026, April through June, is the first full quarter in which the KSeF requirement applies to nearly all Polish VAT-registered companies. The invoices you received from Polish suppliers in Q2 2026, which you wish to submit for VAT refund, should in most cases be KSeF invoices.

For your refund covering Q2 2026, for which the deadline is 30 September 2027, it is important to verify that the submitted invoices meet the new requirements.

Did you receive invoices in Q2 2026 without a KSeF number from a Polish supplier subject to the requirement? Contact your supplier to obtain the correct KSeF version before submitting your refund claim.

Let professionals guide you

The introduction of KSeF adds a new layer to the already complex VAT refund procedure in Poland. Which invoices are valid, how do you verify a KSeF number, and what do you do if your supplier fails to comply with the requirement?

Delta Refund Solutions closely monitors these developments and ensures your file is compliant with the latest Polish requirements.

Feel free to contact us, we are happy to help.