How to issue a KSeF invoice correction without errors?

You sent an invoice through KSeF (Poland's national e-invoicing system), it received a KSeF number, and only then you notice that two digits in the buyer's NIP (Polish tax ID) are swapped. Before KSeF, a buyer could have fixed this with a correcting note. Today a KSeF invoice correction is the only way out: the system does not let anyone edit, cancel or delete an accepted invoice (KSeF 2.0 Manual, part II).

The timing matters. From 1 January 2027, the smallest businesses (those issuing up to PLN 10,000 gross in invoices per month) must use KSeF too (jpk.info.pl). Under the current act, penalties start on the same date. The government proposes moving them to 1 January 2028 (Sejm print no. 3245), and the Sejm passed the bill on 6 November 2026 (Rzeczpospolita). As of 10 November 2026 it is not yet law.

Below: which fields to fill in, how to fix the four most common mistakes, and when to report the correction in VAT.

What you cannot do with a KSeF invoice

Once KSeF assigns a number, the invoice is legally in circulation. Only the seller can fix it, by issuing a corrective invoice (KSeF 2.0 Manual, part II). A correction undoes nothing. It adds a second document linked to the first.

The buyer has no say. The buyer-issued correcting note (nota korygująca) has not been available since 1 February 2026 (wFirma help, Ministry of Finance Q&A). Even a typo in an address has to be corrected by the seller.

Two pieces of good news. An invoice counts as received by the buyer the moment KSeF assigns its number (Ministry of Finance interpretation, 1 July 2026). And there is no limit on how many corrections you can issue to one invoice (MF Q&A, question 22).

What a KSeF invoice correction is made of

In the FA(3) structure (the XML format of Polish e-invoices), a correction has one of three types: KOR (standard), KOR_ZAL (correcting an advance invoice) or KOR_ROZ (correcting a settlement invoice) (MF, module III). The key block is DaneFaKorygowanej, where you identify the original invoice: issue date, the number you gave it, and its KSeF number. The KSeF number is required if the original received one (MF interpretation). You never list earlier corrections, only the original (KSeF 2.0 Manual, part II).

Which fields you fill depends on where the original was issued:

• in KSeF: NrKSeF = 1 and NrKSeFFaKorygowanej with the KSeF number,

• outside KSeF (for example, issued before the obligation applied to you): NrKSeFN = 1, no KSeF number.

A shortened XML fragment for a correction of a KSeF invoice (other fields required by the schema omitted):

<Fa>
  <P_1>2026-11-10</P_1>
  <P_2>KOR/11/2026/001</P_2>
  <RodzajFaktury>KOR</RodzajFaktury>
  <PrzyczynaKorekty>Wrong VAT rate on line 2</PrzyczynaKorekty>
  <TypKorekty>1</TypKorekty>
  <DaneFaKorygowanej>
    <DataWystFaKorygowanej>2026-11-03</DataWystFaKorygowanej>
    <NrFaKorygowanej>FV/11/2026/014</NrFaKorygowanej>
    <NrKSeF>1</NrKSeF>
    <NrKSeFFaKorygowanej>9999999999-20261103-6ED7929702D8-54</NrKSeFFaKorygowanej>
  </DaneFaKorygowanej>
  <!-- correction lines: before / after state -->
</Fa>

A classic trap: typing your own invoice number (say FV/11/2026/014) into the KSeF number field. They are two different numbers (MF Q&A). In an interpretation of 20 May 2026, the Director of the National Tax Information (KIS) confirmed that when the original was issued outside KSeF, this field stays empty, and your own number must not go there (summary on jpk.info.pl).

TypKorekty is optional but worth filling: 1 means the correction takes effect on the date of the original invoice, 2 on the date the correction is issued, 3 on another date (KSeF 2.0 Manual, part II). You can show the changes as "before / after" lines or as reversal (storno) lines, where the original line is repeated with a minus sign.

A single collective correction (for example, an annual rebate) can cover up to 50,000 original invoices, but you must list each one with its number, date and KSeF number (MF Q&A, question 24). Skipping DaneFaKorygowanej and moving that data into an attachment is explicitly the wrong approach (KSeF 2.0 Manual, part III).

Four situations and how to fix them

I write as the founder of an invoicing SaaS, not as a tax adviser. Confirm the VAT treatment of each correction with your accountant.

Wrong amount, VAT rate or line item

This is a standard KOR correction. If it reduces the tax base (a rebate, a return, a price cut), it is an "in minus" correction. A seller who issues it as a structured invoice in KSeF reduces the tax base and output VAT in the period in which the correction was issued, without needing documentation of an agreement with the buyer (prawo.pl, art. 29a(15)(5) of the VAT Act). The buyer reduces input VAT in the period in which the correction received its KSeF number (jpk.info.pl). For an "in plus" correction, the period depends on the cause of the error. Set TypKorekty and ask your accountant.

Wrong buyer NIP

A standard correction will not work here: an incorrect buyer identification number cannot be corrected (KSeF 2.0 Manual, part II). If the wrong NIP belongs to another company, the invoice is visible in that company's KSeF. According to the Ministry of Finance, you issue a corrective invoice that zeroes out the original (still showing the wrong NIP) and then a new invoice with the correct NIP (MF Q&A, question 23).

Example for a Polish subsidiary invoicing a group company. Invoice FV/11/2026/014 of 3 November 2026: PLN 8,000 net, PLN 1,840 VAT (23%), PLN 9,840 gross, issued to the wrong group entity because the NIP was taken from the wrong contract. You issue:

1. A zero correction against the wrong NIP: minus PLN 8,000 net, minus PLN 1,840 VAT, minus PLN 9,840 gross.

2. A new invoice with the correct NIP for the same amounts.

Which period? In an interpretation of 18 June 2026 (0112-KDIL1-3.4012.269.2026.1.KK), KIS held that because the cause of the error existed on the day the original was issued, the correction belongs in the original invoice's period, not the month of the correction (podatki.biz). In practice this can mean amending the JPK_V7 (the monthly VAT return file) for that month. Interpretations cover specific facts, so check your case with your accountant.

Wrong invoice number, date or address

For a wrong invoice number, the wrong number goes into NrFaKorygowanej and the right one into NrFaKorygowany (KSeF 2.0 Manual, part II). Note that sending invoices to KSeF out of numbering order is not a reason to issue a correction (KSeF 2.0 Manual, part II). To fix a buyer's name or address (anything other than the NIP), you include the buyer's full data from the original invoice in the buyer section.

An invoice from offline24 mode, an outage, or outside KSeF

If the original was issued in offline24 or emergency mode, first send it to KSeF so it gets a number, and only then issue the correction (KSeF 2.0 Manual, part III). An invoice sent by mistake needs a correction too. The Ministry confirmed this for a company that mistakenly sent 2,568 pre-obligation invoices to KSeF on 24 March 2026 (MF interpretation).

Checklist before you send a correction

1. Check whether the original has a KSeF number: if yes, NrKSeF = 1 plus the number; if not, NrKSeFN = 1.

2. Copy the KSeF number from your invoice list or the UPO (the official confirmation of receipt). Never type your own invoice number there.

3. Identify the error type: amount, rate, NIP, number or data. For a wrong NIP, issue a zero correction and a new invoice.

4. Set TypKorekty (1, 2 or 3) so it is clear in which period the correction applies.

5. For offline24 or outage invoices, wait until the original gets its KSeF number.

6. After sending, save the correction's KSeF number and UPO.

7. Ask your accountant whether a JPK_V7 correction is needed for the original invoice's period.

Conclusion

A KSeF correction is a new document tied to the original by its KSeF number, not an edit. Watch three things: the right KSeF number of the original, the right correction type (standard or zero), and the right settlement period.

In Biurko, you create a correction from an issued sales invoice. You pick correction type 1, 2 or 3, enter the reason, and for a wrong NIP you prepare a zero correction in one action. You review the draft before it goes to KSeF. Try Biurko free for 14 days at biurko.io.

FAQ

Can you delete or cancel an invoice in KSeF?

No. Once KSeF accepts an invoice and assigns a number, it cannot be cancelled, deleted or edited. The invoice enters legal circulation, and the only way to fix an error is a corrective invoice issued by the seller (Ministry of Finance). If the invoice should never have existed, you issue a zero correction.

Can I issue a correcting note in KSeF?

No. Since 1 February 2026 a buyer can no longer issue a correcting note, because the instrument no longer applies (wFirma help). If an invoice contains an error, the buyer asks the seller for a corrective invoice. This applies even to minor slips such as a typo in an address or company name.

How do I fix a wrong buyer NIP in KSeF?

A standard correction is not enough. According to the Ministry of Finance, you issue a corrective invoice that zeroes out the invoice showing the wrong NIP, then a new invoice with the correct NIP (MF Q&A, question 23). Confirm the period for both documents with your accountant, since KIS interpretations point to the original invoice's period.

How many corrections can one KSeF invoice have?

There is no limit. The Ministry says you can issue as many corrections as needed until the document is finally correct (MF Q&A, question 22). Each correction points to the original invoice in DaneFaKorygowanej, not to the previous correction. A collective correction covers up to 50,000 original invoices, each listed with its KSeF number.

How is an "in minus" KSeF correction settled for VAT?

The seller reduces the tax base and output VAT in the period in which the correction was issued in KSeF, without a confirmation of receipt from the buyer (prawo.pl). The buyer reduces input VAT in the period in which the correction received its KSeF number (jpk.info.pl). For offline or outage modes, check the detailed rules with your accountant.