Check where your company has gaps in KSeF
5 short questions about how KSeF really runs for you today. In return: a list of concrete gaps and what's worth fixing first.
AuthorAdrian HuniaOwner, leads the technical sideWhat usually breaks once KSeF is actually live
Companies that rolled out KSeF before the deadline often did it the simplest way possible: export a file from the accounting software and upload it to the Ministry of Finance's platform by hand. That works, but every extra invoice means a few more minutes of manual work, and at higher volume that work can eat a full-time role.
The second, less-discussed problem is the offline mode. KSeF has outages and scheduled maintenance windows, and the Ministry of Finance built an offline procedure for exactly that: its own invoice numbering and a deadline to submit invoices to the system once it's back. Companies without a written procedure for that day end up improvising under time pressure.
The third, most commonly skipped piece is receiving cost invoices. Companies usually sort out sending their own sales invoices first, and leave receiving invoices from suppliers for later, sometimes forever. The result: a cost invoice sits in KSeF, and nobody in the company knows it ever arrived.
The protection period ends for everyone on 1 January 2027, and from that day the law provides an administrative penalty of up to 100% of the VAT on an invoice issued outside KSeF against the obligation, and 18.7% of the total amount due on invoices without VAT. From 1 January 2027 a separate penalty of 500 PLN per document also applies to invoices submitted to the system late from offline or emergency mode. An invoice rejected by KSeF counts as never issued.
The obligation covers every VAT taxpayer with a Polish tax ID, both VAT-registered and VAT-exempt. Large taxpayers, with 2024 gross sales above 200 million PLN, joined KSeF on 1 February 2026, and everyone else on 1 April 2026, VAT-exempt companies included. Only the smallest taxpayers have until 1 January 2027, those whose total sales stay at or below 10,000 PLN gross per month, and they may invoice outside KSeF until 31 December 2026. The criterion is the size of your sales, not your VAT status, so being VAT-exempt on its own defers nothing.
Answer 5 questions
The score comes from five areas where KSeF rollouts most often have gaps: how you issue invoices, how automated it is, your outage procedure, how cost invoices come in, and error monitoring. Every answer updates the result on the right instantly. At the end, leave an email or phone number if you'd like help closing the gaps.
Needs urgent attention
A few key parts of your KSeF setup aren't working the way they should yet.
- Work out with your software vendor (or with us) how to turn manual export and upload into automatic KSeF submission.
- Write down a procedure for a KSeF outage or scheduled downtime: backup invoice numbering and a deadline to submit once the system's back.
- Set up automatic receiving of cost invoices from KSeF so they land straight in your books instead of sitting unnoticed in the system.
- Ask your vendor exactly what part of the integration still needs manual work, and agree a date for when that goes away.
- Assign one person to keep an eye on KSeF rejections and errors on an ongoing basis.
What to do regardless of your result
Check with your accountant whether you have a written procedure for a KSeF outage or scheduled downtime, including backup numbering and a deadline to submit invoices once the system's back.
Ask your software vendor whether cost invoices from suppliers reach your books automatically, or whether someone has to pull them from KSeF and upload them by hand.
Check with your software vendor whether KSeF rejections and errors show up anywhere in your system, or whether someone has to check the platform manually.
Assign one person to keep an eye on KSeF rejections and errors, without an owner, problems only surface at VAT settlement time.
Frequently asked questions
Q.1Is it normal that long after the obligation started we're still manually exporting and uploading invoices to KSeF?
Yes, it's very common. Many companies rolled out KSeF the simplest way possible to make the deadline, and put full integration off for later. That works while invoice volume is low, the problem shows up once the workload grows faster than anyone has time for.
Q.2We don't have a procedure for a KSeF outage. What happens if the system is offline right when we need it?
The Ministry of Finance built an offline mode for exactly this case, with its own invoice numbering and a deadline to submit invoices once the system is back. Without a written procedure, a company usually improvises on the day, which raises the risk of numbering mistakes and late submissions.
Q.3What happens if a cost invoice never reaches us because nobody's checking KSeF?
It sits in the system, and you don't know it arrived until someone asks the supplier or the document turns up missing at settlement time. Receiving cost invoices needs to be set up as deliberately as sending your own sales invoices, it doesn't happen on its own.
Q.4What's the difference between partial and full KSeF integration?
Full integration means your accounting or ERP software sends and receives invoices without anyone touching them. Partial usually means the system generates the invoice, but someone still has to approve, send, or download confirmation by hand, and every invoice costs a few minutes of someone's time until that's fixed.
Q.5Who in the company should be monitoring KSeF rejections and errors?
Ideally one specific person, usually in accounting, who checks the status of sent and received invoices regularly. Without that, a rejected invoice can sit unnoticed for weeks, which complicates VAT settlement.
Q.6Will our accounting software just warn us when something goes wrong in KSeF?
Depends on the vendor. Some systems show invoice status and errors right in their own interface, others require checking the Ministry of Finance's platform manually. Worth asking the vendor directly rather than assuming the system handles it.
Q.7We've had KSeF since April 2026 and everything looks like it's working. Why bother with this check?
Because 'looks like it's working' and 'runs without manual work and without holes' are two different things. This check looks specifically at your outage procedure, cost-invoice handling, and error monitoring, the three places companies most often have a gap, even while formally settling through KSeF.
Q.8We're small and VAT-exempt. Does KSeF apply to us?
Yes, it does. Being VAT-exempt does not defer the obligation, VAT-exempt companies joined KSeF on 1 April 2026 just like VAT-registered companies of the same size. Only the size threshold defers it: with total sales up to 10,000 PLN gross per month you may invoice outside KSeF until 31 December 2026, whatever your VAT status. If you're above that threshold, the obligation has applied to you since April 2026 at the latest, and this check shows where the gaps are.
