Creditnote in KSeF and Peppol

You issue an invoice, send it through the system, and then notice an error: an incorrect amount, a typo in the customer’s details, the wrong VAT rate or a mistake in the tax identification number. In the past, many business owners simply edited the file, sent a new PDF or verbally agreed with the customer that the earlier version “never existed”. In the age of e-invoicing, this approach no longer works.

Once sent, a structured invoice — whether through Poland’s KSeF or the European Peppol network, already used by businesses in Belgium — becomes part of the formal document exchange process. It is not a file you can quietly replace, but a document with its own identifier and a traceable record in the system, visible to the other party in the transaction.

The good news is that errors can still be corrected. You simply need to use the proper procedure: issue a creditnote.

Why a structured invoice cannot be edited

An e-invoice is not a PDF with a number at the top of the page. It consists of data stored in a precisely defined XML structure, submitted to a system, identified and passed on according to an established standard.

In KSeF, a document that has been assigned a number enters the official tax records and can no longer be edited, cancelled or deleted. The only way to correct an error is to issue a creditnote.

This makes it possible to track every change and clearly link it to the original document, so the accountant, customer and tax authority always know what was issued first and what was corrected.

The same principle applies in Peppol, although the scope of mandatory use varies by country.

In the Netherlands, Peppol is required only for transactions with public authorities (B2G), while its use in B2B remains voluntary, despite being widespread. In Belgium, it has also covered B2B transactions since 1 January 2026. A business working with partners in different markets may therefore already face different requirements depending on the customer’s country.

The Peppol BIS Billing 3.0 standard supports both invoices and creditnotes that refer directly to the original invoice.

The practical rule is the same, regardless of the system: once an invoice has entered the formal document exchange process, do not treat it as a draft. If something is incorrect, issue a correction.

When should you issue a creditnote?

You issue a correction whenever, after issuing the original invoice, you need to correct details or change the value of the transaction. Examples include an incorrect price, the wrong VAT rate, a discount granted after the sale, returned goods, a customer complaint, an error in the buyer’s details or an incorrect identification number.

What must a creditnote in KSeF contain?

In KSeF, a creditnote must contain its own number and issue date, the original invoice’s KSeF number if one has been assigned, details from the original invoice, a description of the goods or services covered by the correction, and either the adjustment amounts or the correct content of the items being amended.

Downward and upward corrections

From an accounting perspective, the more important distinction is between a downward correction (in minus), which reduces the taxable amount or VAT — for example, following a discount, returned goods or an overstated amount — and an upward correction (in plus), which increases those values, for example when an additional service is charged or the wrong rate was used on the original invoice.

Do not judge a correction solely by whether the customer pays extra or receives a refund. Check exactly what changes in the data: the taxable amount, VAT, the total amount including VAT, the buyer’s details or the item description.

An amended PDF does not replace a correction in the system

If an invoice has already been submitted to KSeF and accepted, emailing an amended PDF to the customer does not formally change anything. The customer may already have recorded the original document in their accounts, their accountant may already have seen it in the system, and the tax authority has access to it regardless of what happens in your email correspondence.

If a separate “new version” appears alongside it, this creates unnecessary confusion: which invoice is correct, which one should be recorded, and how much should ultimately be paid?

The same rule applies to Peppol. Once a document has entered the network as an invoice in a particular standard, the correction should follow the same organised channel, rather than arrive in an email inbox as an informal amendment.

How are invoices sent through Peppol, and how does this differ from sending a PDF? Read more HERE.

Corrections in KSeF without confirmation of receipt

This is a practical difference compared with traditional invoice exchange, where you had to keep track of whether the customer had received the correction and when it could be accounted for. In KSeF, what matters is when the document is issued in the system. The correction receives a number and immediately becomes available to the buyer, without requiring any additional confirmation from them.

For you, this means less administrative tracking of who received what and when. However, good communication still matters. If the correction changes the amount payable, results in a refund or requires an additional payment, a short message to the customer is still useful. For example, you can explain the reason for the correction and ask them to record the updated document.

The end of buyer-issued correction notes

Since 1 February 2026, correction notes (noty korygujące) have no longer operated in their previous form. Previously, the buyer could correct a minor formal error on an invoice, such as a typo in the name or address, by issuing a correction note without the seller’s involvement.

This option is no longer available. If the customer notices an error, they can only report it. Correcting the document is now solely the seller’s responsibility, through a creditnote issued in KSeF.

This places responsibility for the quality of invoice data on your side. The more carefully you check the details before sending, the fewer corrections you will need to issue later.

How to issue a creditnote step by step

1. Select the original invoice

In eFaktura.nl, start by finding the original invoice in the invoice list and opening the three-dot menu next to it. You will find the “Issue a creditnote” option there. This starts the correction process, regardless of whether the original was sent through KSeF or Peppol.

2. Review the document prepared by the system

The system automatically reverses the amounts from the original invoice to negative values, copies the customer’s details and adds a reference to the invoice number in the notes, for example, “Creditnote for invoice 2026/0001”.

This reference links the two documents in the system, so you do not have to enter it manually.

3. Set the scope and reason for the correction

Before saving the document, adjust it to reflect the actual situation.

If you are correcting only part of the invoice — for example, one item or a price difference — change the amounts so they reflect only the adjustment, rather than the entire original invoice.

If the error concerns the whole document, leave the correction as prepared by the system, as a full reversal.

In the notes field, replace the general term “creditnote” with a specific reason, such as a discount, returned goods or an incorrect VAT rate.

4. Send the correction

Finally, send the document through the same channel as the original — KSeF or Peppol — using the same menu where you issued the creditnote. If the correction changes the amount payable, it is also worth emailing it to the customer or briefly explaining what has changed.

5. Inform the customer

Throughout the process, remember the customer if the correction affects payment. In eFaktura.nl, the system automatically emails them a preview of the correction together with information identifying the earlier invoice it relates to, so an additional message from you is not necessary in this case.

Special cases

When KSeF rejects an invoice file

This is fundamentally different from an error on an accepted invoice and is a common source of confusion. If the system rejects the XML file, the invoice has not formally been issued, so there is nothing to correct yet.

In this situation, correct the file and submit it again as a new invoice, rather than as a correction.

The distinction is simple: an accepted invoice with an assigned KSeF number requires a correction if it contains an error, while a rejected file simply needs to be corrected and resubmitted.

An incorrect buyer identification number

This is one of the more problematic cases in KSeF, because a document with an incorrect NIP number may be assigned to an entirely different entity if that number exists in the system.

The solution is to issue a creditnote reducing the original invoice to zero, using the incorrect number, and then issue a new original invoice with the correct details.

For businesses working with Polish customers, this means one thing: verify the company’s NIP number before sending, not afterwards. Checking a new customer’s details before issuing their first invoice is a good habit, particularly when the customer is based in another country and differences in format or typos make mistakes more likely.

Several corrections to one invoice

You can issue more than one correction to the same document if the situation requires it. The system does not limit this.

What matters more than the number of corrections is that each subsequent one is clearly described and correctly linked to the document it concerns.

The more corrections accumulate around a single invoice, the more useful it becomes to keep the numbering, dates and reasons organised. Otherwise, it is easy to lose track, especially when someone outside your business, such as an external accounting firm, reviews the documents.

Creditnotes in Peppol

In Peppol, corrections are handled using a document called a creditnote. It is used to correct or reduce an earlier invoice and may refer to one or several original invoices at the same time.

The terminology varies depending on the country and accounting system. It may be called a creditnote, a correction or a negative invoice, but the underlying principle remains the same as in KSeF: there is an original document, an error or change occurs, and you issue a creditnote with a clear reference to the original. You never replace the original invoice.

Good invoicing software should guide you through this process according to the standard applicable in the country concerned, regardless of the local name for the document type.

The most common mistakes when issuing corrections

1. Sending an amended PDF instead of a correction through the system. A PDF can serve as a preview for the customer, but it does not replace a creditnote.
2. Omitting the original invoice’s KSeF number from the correction. This makes it harder to link the correction to the document it concerns.
3. Giving an overly general reason for the correction. The word “error” alone does not explain what has changed.
4. Confusing a rejected file with an accepted invoice. Each situation requires a different action.
5. Failing to inform the customer about a change in the amount payable. The customer should know whether the correction means an additional payment or a refund.

How to prepare your business for corrections in e-invoicing

The aim is not to worry about KSeF or Peppol, but to adjust a few habits in your daily work.

Check the customer’s details, especially their identification number, before issuing an invoice. Verify the amounts and VAT rate before sending, and do not try to amend the document manually or by email after it has been sent.

If an error occurs, issue a creditnote through the same channel as the original. Consult your accountant about more significant changes, and inform the customer whenever the correction affects payment.

Why should you check your customer’s VAT status before issuing an invoice? Read more HERE.

There is also one simple organisational rule: keep consistent numbering and clear reasons in the document history, so you can easily reconstruct what happened months later.

You do not need to feel stressed about correcting electronic invoices. It is a normal procedure, not a system failure, and you can work through it without difficulty. Every error can be put right, and in more complex cases, it is always worth asking your accountant for support.