The National e-Invoicing System (KSeF) is a nationwide ICT platform used to issue, receive and store so-called structured invoices. In practice, this means that a sales document takes a uniform electronic format and is transmitted directly to the tax administration system, increasing transparency of settlements and automating document circulation.
The obligation to use KSeF is being introduced in stages. From 1 February 2026, the National e-Invoicing System covered the first group of VAT taxpayers (primarily larger entities). In the following months, the requirement will be extended to other entrepreneurs conducting business activity. Ultimately, most VAT taxpayers in Poland will be required to issue invoices exclusively through KSeF.
Introducing this obligation is not only a change in how sales are documented, but also brings new challenges in everyday practice. Although a transitional period applies until the end of 2026 and penalties for failing to issue structured invoices have been postponed, it is worth preparing now for the full digitalisation of accounting processes.
It is therefore no surprise that many questions and doubts are arising among accountants and entrepreneurs. Below we address the most common ones.
1. Does an invoice received outside KSeF – even though it should have been issued in the system – still allow VAT deduction?
Yes, an invoice issued outside KSeF still gives the right to deduct VAT.
According to the position of the Director of the National Tax Information (KIS), the key factor is that the invoice:
- documents an actual economic transaction,
- is related to taxable activity,
- and no negative conditions under Article 88 of the VAT Act apply.
A breach of the seller’s obligation to issue the invoice via KSeF does not deprive the buyer of the right to deduct VAT — any potential sanctions apply to the issuer, not the recipient of the invoice.
2. Should corrective invoices concerning only formal data (e.g. bank account number, GTU codes, payment deadline) be included in the JPK_VAT file?
KSeF does not provide for issuing corrective notes. This means that:
- the buyer can no longer correct an invoice using a corrective note (as was possible outside KSeF),
- all errors - both formal and substantive - must be corrected solely by the seller through a corrective invoice issued in KSeF.
However, if the correction does not affect information previously reported in the JPK_V7 file (e.g. it only concerns the bank account number or payment deadline), the buyer does not need to reflect such a correction in tax settlements.
If the correction relates to data previously included in JPK_V7 and adjusts incorrect values, an appropriate correction of the file is required.
3. Which structure should be used when correcting JPK files for earlier periods (up to February 2025): JPK_V7M(2)/JPK_V7K(2) or the newer JPK_V7M(3)/JPK_V7K(3)?
When submitting a correction of the JPK_V7 file, the same structure should be used as in the original VAT return. Therefore, when correcting January 2026, the structure JPK_V7M(2)/JPK_V7K(2) should be applied.
4. If there is no obligation to send invoices to KSeF, should the BFK marker still be used for sales invoices?
Yes. Even without the obligation to issue structured invoices, when issuing paper or electronic invoices they should still be marked as BFK in the JPK_V7 file.
5. Can invoices issued outside KSeF and dated before 1 February 2026 be corrected using a corrective note?
No. From 1 February 2026, corrective notes are no longer applicable - even for invoices issued earlier outside KSeF.
Transitional provisions still allow the use of corrective notes that were physically issued before February 2026. In all other cases, any error identified later must be corrected by the seller through a corrective invoice.
6. Should invoices issued in KSeF between related entities be marked as related-party transactions (TP) and included in JPK_VAT with this designation?
Transactions between related entities must be included in VAT records and in the JPK_VAT file with the TP marker.
However, including the TP designation on the invoice itself in KSeF is optional.
7. After mandatory KSeF enters into force, will it still be possible to issue duplicate invoices?
No. After the mandatory KSeF comes into effect, duplicate invoices will disappear from circulation because all structured invoices will be stored in KSeF for 10 years and taxpayers will have continuous access to them.
This means invoices can no longer be “lost” or “destroyed”, eliminating the need to issue duplicates.
Need support with KSeF?
If you have doubts about:
- whether your invoices must be issued through KSeF,
- how to correctly deduct VAT from invoices received outside the system,
- how to include corrections in JPK_V7,
- or how to prepare your accounting processes for full digitalisation,
contact us - we will help you implement KSeF safely and efficiently in your business.