KSeF correction invoices from the accounting office's side: no more notes, the wrong NIP, and the correction you're still waiting for

The Note Is Gone

For years the quickest fix in an accounting office was the correction note. The supplier misspelled the client's street or got the payment date wrong, so the buyer issued a nota korygująca, the supplier accepted it, and that was the end of it. Five minutes, no phone call to the supplier's billing department.

That's over. Article 106k of the VAT Act was repealed with effect from 1 February 2026. Since then every error on an invoice, even a typo in an address, is fixed by the seller with a correction invoice. It doesn't matter whether the original went through KSeF or not. The buyer can no longer fix anything on their side.

This sounds like a paperwork detail. For an office it changes who holds the pen. Every mistake your clients receive now becomes a request to someone else's billing department, and a wait. Someone at your office has to remember they're waiting.

Yesterday I wrote about offline24 invoices, the ones that fall between two download runs. Corrections are the other half of the month-end mess: documents that point backwards, to invoices you may have booked, filed, or never received.

Three Documents for One Typo

The case that surprises offices most is the wrong buyer NIP.

Before KSeF a wrong NIP was a formal error, usually settled with a note. In KSeF the NIP is also the delivery address: whoever holds that NIP gets the invoice in their KSeF. So an invoice sent to the wrong NIP doesn't just carry a mistake. It gets delivered to a company that bought nothing.

The Ministry of Finance's answer is three documents. The original with the wrong NIP stays in KSeF, since nothing in KSeF can be deleted. The seller issues a correction to zero against it. Then they issue a new invoice to the correct NIP. A normal correction can't move an invoice to a different buyer; the structure doesn't allow it.

Here's what that looks like inside your office, depending on which side your client is on.

If your client is the seller: the correction to zero belongs in the same period as the original, because the error existed from the day the invoice was issued. If the original is in a JPK already filed, that JPK needs a correction. The new invoice goes into its own period. A seller who issued on the 28th, noticed on the 3rd and fixed it on the 4th now has documents in two months and a JPK to reopen. I wrote about how those corrections work, and what an agent won't do there, in JPK_V7 corrections.

If your client is the wrong buyer: an invoice from a supplier they've never dealt with appears in their KSeF. If your download books everything that arrives, it's now a cost in their ledger. A few days later a correction to zero arrives. If both landed in the same month, the net effect is nothing and you only have noise. If they straddle a month-end, you've deducted VAT on a purchase that never happened and have to reverse it next month.

If your client is the right buyer: they're still waiting for their invoice. It shows up only when the seller gets round to the third document.

What a Correction Points At

A correction invoice in KSeF carries the KSeF number of the invoice it corrects. That's the good news: in principle, pairing a correction with its original is a lookup, not guesswork.

There's one exception. If the original was issued outside KSeF, for example before the client's KSeF obligation began on 1 February or 1 April, or during a total failure, the KSeF number field stays empty. The rules say it must stay empty rather than hold a placeholder. The link then rests on the original's invoice number and issue date, the way it always did.

You'll see plenty of those for the rest of 2026: corrections issued in KSeF against invoices from January or March that never went through it. That's where automatic pairing fails, because "FV/03/112" from one supplier can match three documents if their numbering restarts each year.

Two more things matter for timing:

• For the buyer, a correction received through KSeF is received on the date KSeF gives it a number, the same rule as for any other invoice.
• A correction that reduces the price and one that fixes a wrong NIP don't necessarily go into the same period. The first usually follows the correction date; the second goes back to the original. Your software won't tell you which is which. The reason field on the correction might, if the supplier filled it in.

Three Lists Worth Generating Every Night

Most of this doesn't need judgement. It needs a list that somebody reads. This is the read-only check I build for offices:

1. Unpaired corrections. For every correction downloaded in the last 10 business days, find the original in the client's books: by KSeF number, or by number plus issue date when the number field is empty. Anything with no match goes on the list, split into "original not downloaded", "original predates KSeF, check by hand" and "several possible matches".
2. Pairs that net to zero. Original plus correction equals zero. Each one is either a cancelled sale or a wrong-NIP case. If the two documents sit in different VAT periods, or the original is in a JPK already filed, the pair goes to the top of the list. On the buyer's side, add a filter for suppliers the client has never bought from before; that's how the wrong-NIP invoice usually shows itself.
3. Corrections you're waiting for. Now that notes are gone, bookkeepers mark purchase invoices as "correction requested". The agent checks nightly whether a correction pointing at that KSeF number has arrived. After 14 days without one, the invoice goes back to the person who asked, with the supplier's name and the date of the request.

The agent books nothing, corrects nothing and never writes to a supplier. It hands a named person three short lists: client X, correction to zero for an invoice in the filed August JPK; client Y, two corrections with no original; client Z, waiting 16 days for a correction from a courier company. The rest is a phone call.

If you're still deciding where your downloads come from, start with automatic KSeF invoice downloads. This check sits on top of them.

Two Numbers for This Week

1. How many corrections did your clients receive in September, and how many of them can you pair with an original without opening a PDF? The gap between those two numbers is roughly your manual work each month.
2. How many purchase invoices are waiting for a correction right now, and who is tracking them? If the answer is "the bookkeeper remembers", the answer is really "nobody".

If you'd like the nightly version of these lists set up in your office, write to me. It's usually the third check I set up in an office, after access and offline invoices.