New KSeF obligations and the problem of incorrect invoices
From 1 April 2026, some VAT taxpayers are required to issue invoices through the National e-Invoicing System (KSeF). Introducing the new system means adapting internal accounting procedures, which in practice raises many questions about how to handle documents that contain errors.
One of the most common problems arises when a business prepares an invoice in its accounting system and then, before sending it to KSeF, discovers irregularities. These may involve an incorrect amount, an inaccurate description of the service, a mistake in the customer's details or other elements of the document that need correcting.
The key question then is whether such a document should nevertheless be entered into KSeF and corrected afterwards, or whether it can simply be deleted from the accounting system. The latest individual interpretation of the Director of the National Revenue Information (KIS) of 9 June 2026 sheds light on this issue and sets a clear line that determines whether an invoice may be cancelled.
When does an invoice enter legal circulation? The key moment for a business
In its position, the tax authority drew attention to a fundamental point - an invoice is a formal document that confirms a specific business event and produces particular tax consequences. It is therefore not merely a technical entry in accounting software. Of particular importance here is Article 108(1) of the VAT Act, which provides for an obligation to pay the tax shown on an invoice where the taxpayer validly issues a document containing a tax amount.
The tax authority stressed that simply drawing up a document in the accounting system does not always mean it has been issued within the meaning of the tax rules. What matters is the moment the invoice is passed to another party and enters legal circulation. As long as the document remains an internal proposal - a draft invoice that has not been made available to the customer or sent to KSeF - it has no tax consequences.
This distinction is of great practical importance. A business that spots an error during internal verification does not have to enter the faulty document into KSeF just to issue a correction to it afterwards. It is enough to delete the incorrect draft invoice from its accounting system.
Cancelling an invoice - an exceptional procedure with limits
It is worth stressing that the VAT Act does not expressly regulate a procedure for cancelling invoices. This option has developed through interpretive and case-law practice, but it is subject to significant limitations. The Director of KIS stated unequivocally that cancellation should be treated as an exceptional solution, not a standard method of correcting documents.
Conditions for cancelling an invoice
Based on the tax authority's position, the following conditions can be identified, all of which must be met for cancelling an invoice to be permissible:
- The invoice has not entered legal circulation - it has not been passed to the customer in any form or sent to KSeF.
- The document does not record a transaction that was actually carried out - e.g. it contains an incorrect description of the service, wrong amounts or relates to a transaction that did not take place.
- The business has exercised due diligence - cancellation cannot replace a proper process for documenting business events.
- The document is still at the internal drafting stage - e.g. it has not yet gone through the approval procedure in the company's accounting system.
If these conditions are met, the business is entitled to delete the erroneous document without entering it into KSeF and without issuing a credit note (corrective invoice). This is a significant simplification that avoids unnecessary bureaucracy where a mistake is caught early enough.
Once sent to KSeF, cancellation is impossible - correction is the only option
The situation is quite different once the XML file has been sent to the National e-Invoicing System, accepted by the system, and the invoice has been given a KSeF identification number. In that case the document is considered to have entered legal circulation, and cancelling it is no longer possible.
KSeF does not technically allow an invoice accepted by the system to be cancelled. The moment the document is sent and accepted is therefore a point of no return - once it has passed, the only solution available is to issue a credit note (corrective invoice).
When is a corrective invoice required?
Under the VAT Act, a corrective invoice is issued in particular where:
- The taxable amount or the amount of tax shown on the invoice has changed.
- A mistake in any item of the invoice has been found - this includes, among other things, an incorrect price, VAT rate, customer details or description of the goods or services.
- After the invoice was issued, there were changes affecting the actual business event - e.g. a discount was granted, goods were returned or the contract was withdrawn from.
A correction is therefore a tool for bringing the original invoice into line with reality. At the same time - and this is important - a correction is possible only where an original invoice exists that has validly entered legal circulation. If the document never left the business's accounting system, there is no basis for issuing a correction.
Practical conclusions for businesses using KSeF
The position of the Director of KIS, set out in the individual interpretation of 9 June 2026 (no. 0114-KDIP1-1.4012.220.2026.2.AWY), has specific practical consequences for businesses required to use KSeF. Above all, businesses should pay particular attention to internal document approval procedures before documents are sent to the system.
Introducing multi-stage invoice verification - covering checks of the customer's details, amounts, VAT rates and service descriptions - will help catch errors at a stage when removing them is still simple and requires no additional formalities. Once a document has been sent to KSeF, every error will require a correction, which creates extra administrative work.
It is also worth remembering that cancellation cannot be used routinely. The tax authorities clearly emphasise the exceptional nature of this procedure. Businesses should exercise due diligence when preparing documents and treat cancellation as a last resort, not a standard part of the invoicing process.
Do you need support implementing KSeF, or do you have doubts about how to document transactions correctly? Contact our firm - our specialists will help you adapt your internal procedures to the new requirements and avoid costly tax errors. Please get in touch by phone or email - an initial consultation will allow us to assess your situation and propose the best solution.
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