Invoice mistakenly submitted to the National System of e-Invoices (KSeF) in Poland – must it be corrected to zero?

An invoice mistakenly submitted to the National System of e-Invoices (KSeF) in Poland after it had already been correctly issued and delivered to the buyer outside the system does not necessarily have to be corrected to zero. The Polish Ministry of Finance (MF) has indicated that a zero correction may not be necessary if both documents can clearly be identified as the same invoice. However, the Director of the National Revenue Information (KIS) adopted a more restrictive approach in an individual tax ruling dated 23 June 2026, requiring the invoice resubmitted to KSeF to be corrected to zero. Businesses should therefore compare the documents carefully and assess the potential risk under Article 108 of the Polish VAT Act.

An invoice may be mistakenly submitted to KSeF particularly during the integration of financial and accounting software or an ERP system with Poland’s National System of e-Invoices. The software may reprocess data relating to documents previously issued outside KSeF and submit XML files for transactions that have already been documented.

This is not merely a technical issue. If the XML file is accepted by KSeF and receives a KSeF number, the business must determine whether a second document has effectively been created, potentially triggering a risk under Article 108 of the Polish Value Added Tax Act (VAT Act). In practice, two different approaches to this issue emerged in Poland in 2026.

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Does an invoice mistakenly submitted to KSeF need to be corrected to zero?

There is currently no single answer that can be applied unconditionally to every case. The approach presented by the Ministry of Finance allows for no correction where it can be clearly demonstrated that the document in KSeF and the invoice previously issued outside the system are, in substance, the same invoice.

The Director of the National Revenue Information (KIS), however, adopted a more restrictive position in the individual tax ruling of 23 June 2026, ref. no. 0114-KDIP1-3.4012.298.2026.1.KP, requiring the mistakenly submitted invoices to be corrected to zero.

The key differences are as follows:

Issue	Approach presented by the Ministry of Finance	Individual ruling issued by the Director of KIS
The invoice had previously been issued and delivered outside KSeF	The later document may be treated as the same invoice	The document submitted to KSeF was considered to have been reintroduced into legal circulation
The data in both documents are consistent	A zero correction may not be necessary	In the circumstances covered by the ruling, the Director of KIS considered a zero correction necessary
The documents differ in material respects	There is a risk that the XML file may be treated as another invoice	This issue was not separately addressed in the ruling
Nature of the position	Ministry of Finance response concerning the specific issue presented	Individual tax ruling issued in a specific case

The final distinction is particularly important. The position presented by the Ministry of Finance should not be treated as equivalent to a general tax ruling or official tax guidance. Likewise, the ruling issued by the Director of KIS does not establish a universally applicable rule for all businesses; it applies to the specific facts presented by the applicant.

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When does the Ministry of Finance say a zero correction may not be necessary?

In its response concerning this issue, presented in July 2026, the Ministry of Finance indicated that where an invoice had previously been issued outside KSeF and entered legal circulation, and its data were subsequently submitted to the system by mistake, a zero correction may not be necessary if it can be clearly established that both documents represent the same invoice.

Particular attention should be paid to whether the following elements match:

• issue date,
• invoice number assigned by the taxpayer,
• date of supply of goods or services,
• invoice line items,
• total amount due.

If the XML file matches the previously issued invoice in these key respects, the Ministry of Finance approach allows the documents to be treated as a single invoice rather than two separate invoices.

This does not, however, mean that a business can automatically disregard every case in which an old invoice reappears in KSeF.

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What if the invoice submitted to KSeF differs from the original invoice?

If the XML file does not correspond to the invoice previously delivered to the customer, the risk is higher. Differences may concern, among other things, the invoice number, dates, sales items or amounts.

Under the approach presented by the Ministry of Finance, the document in KSeF may, following an assessment of the particular circumstances by the tax authority, be treated as another issued invoice. Article 108(1) of the Polish VAT Act may then become relevant, as it concerns the obligation to pay VAT shown on an issued invoice. In such circumstances, correcting the duplicated invoice to zero can reduce the risk of leaving two documents in legal circulation for the same transaction.

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Why did the Director of KIS consider a zero correction necessary?

The individual tax ruling of 23 June 2026 concerned a business that, during system integration testing, mistakenly submitted sales invoices to KSeF that had previously been issued outside the system. The invoices had already been delivered to customers, were in commercial circulation and had been accounted for.

The Director of KIS rejected the taxpayer’s position that resubmitting the documents was purely technical and therefore did not require a correction. The authority concluded that the invoices submitted to KSeF had been reintroduced into legal circulation and should be corrected to zero. According to the Director of KIS, leaving them uncorrected would create a risk under Article 108(1) of the Polish VAT Act.

This ruling is precisely why businesses should not regard the more favourable Ministry of Finance approach as providing complete protection against Polish tax risk.

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Can an invoice simply be deleted from KSeF?

No. A taxpayer cannot independently delete or cancel an invoice that has been accepted by KSeF and assigned a KSeF number.

The current KSeF 2.0 Manual published by the Ministry of Finance states that once an XML file has been accepted and the invoice has received a KSeF number, the document has entered legal circulation. If it contains an error, it must be corrected using a correcting invoice. An invoice that has already been issued cannot simply be edited in the system either; the Ministry indicates that errors should be corrected by the issuer through a correcting invoice. Therefore, where invoices have mistakenly been submitted in bulk, the problem cannot be resolved by technically deleting the incorrect entries from KSeF.

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What should a business do after mistakenly submitting an old invoice to KSeF?

The first step should be to determine the scale of the error and stop further automatic submissions. If the problem results from an ERP or accounting software integration, identifying a single case may indicate that a larger group of historical documents has also been submitted to KSeF.

The business should then:

1. compare the original invoice with the document available in KSeF,
2. verify the invoice number, dates, customer, line items and net, VAT and gross amounts,
3. determine when and how the original invoice was delivered to the buyer,
4. check whether it has already been included in VAT settlements and accounting records,
5. inform the customer about the error to reduce the risk of the same purchase being recorded twice,
6. assess whether a correcting invoice reducing the mistakenly submitted invoice to zero should be issued,
7. eliminate the cause of the incorrect synchronisation or software configuration.

In the current KSeF 2.0 Manual, the Ministry of Finance encourages businesses to implement mechanisms in their invoicing software that check whether an XML file complies with the applicable logical structure before submission. KSeF verifies, among other things, whether the XML file complies with the required structure, but it does not verify mathematical calculations and will not reject an invoice solely because of calculation errors.

Where a larger number of invoices have been submitted by mistake, businesses should also retain documentation showing the cause of the integration error and when it occurred.

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Is correcting an invoice to zero the safer approach?

From a Polish tax risk perspective, correcting the invoice to zero is the more conservative approach, as it is consistent with the solution accepted by the Director of KIS in the individual tax ruling of 23 June 2026. It cannot, however, be concluded that a zero correction is mandatory in every case. The Ministry of Finance approach allows for no correction where the documents are consistent and can clearly be identified as the same invoice.

In practice, before making a decision, the business should answer three key questions:

• Are the two documents genuinely identical?
• Could the customer treat the document in KSeF as another invoice?
• Can the business document that the resubmission was purely technical?

The greater the number of affected documents, the amount of VAT shown or the differences between the invoices, the more important an individual assessment of the appropriate correction method becomes.

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How can businesses reduce the risk of invoices being resubmitted to KSeF?

Cases involving the accidental submission of historical invoices show that KSeF compliance does not end with technically connecting accounting software to Poland’s government e-invoicing system.

Before launching or modifying an integration, businesses should determine in particular:

• from which date documents may enter the submission queue,
• how the system identifies invoices that have already been sent to KSeF,
• whether historical invoices are excluded from automatic submission during data migration,
• who is responsible for monitoring errors and duplicate invoices,
• what procedure applies when a document is submitted by mistake.

Properly managed accounting services in Poland should cover not only the tax and accounting treatment of an invoice, but also controls over the flow of documents between the financial and accounting system and KSeF. This is particularly relevant for businesses managing accounting in Poland through integrated ERP or invoicing systems.

It is also worth reviewing the rules for corrective invoices in KSeF. A corrective invoice is the instrument used to reduce an invoice to zero where, after analysing the circumstances, the mistakenly submitted document should be corrected in this way.

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What is the key takeaway when an invoice is mistakenly submitted to KSeF?

An old invoice mistakenly resubmitted to KSeF should neither be automatically ignored nor assumed to require a zero correction in every case. The Ministry of Finance response indicates that a zero correction may not be necessary where it can be clearly demonstrated that the document submitted to KSeF corresponds to the invoice previously placed into legal circulation. At the same time, the formal individual tax ruling issued by the Director of KIS on 23 June 2026 takes a more restrictive approach and requires a zero correction in the circumstances covered by that ruling.

The key is therefore to compare the two documents, establish the circumstances that caused the error and assess the potential risk under Article 108 of the Polish VAT Act.

If an integration with KSeF has resulted in previously issued invoices being resubmitted, getsix® can support your business in reviewing the documents and VAT settlements and correctly recording any required adjustments in the accounting records. Contact us.

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