Polish Companies Struggle with KSeF E-Invoice Errors as Corrections Reach 20%

KSeF’s Rocky First Six Months

Poland’s Krajowy System e-Faktur (KSeF) has processed over 340 million invoices from more than 2 million taxpayers since going live, but the technological leap is proving far harder than many enterprises expected. Experts warn that up to 20 percent of correction invoices still contain errors, as companies cling to old habits and grapple with the rigidities of the new mandatory environment.

The most persistent problems are mismatches between the PDF visualisation of an invoice and the XML file actually transmitted to the tax authority, duplicate invoices for the same counterparty, and invoices wrongly addressed to a different buyer. Under the old paper-and-PDF regime, many of these mistakes were caught almost immediately and corrected before reaching the counterparty. Now, an erroneous invoice locked into KSeF triggers a multi-step correction process – issuing a correcting invoice, sometimes followed by a brand-new document – which delays settlement and often postpones payments for goods or services already delivered.

Three Technical Fault Lines in the KSeF Rollout

The PDF-XML Gap Carries a Price Tag

One of the most disruptive side-effects is the growing gap between the visual invoice (the print or PDF) and the structured XML data. When the two diverge, the buyer cannot reliably process the document, and the tax office could treat the PDF as a separate, “empty” invoice. That scenario opens the door to a double VAT obligation – once from the KSeF-transmitted invoice and again from the visualisation – a risk that Michał Sosnowski, Business Development Director at Exorigo-Upos, sees materialising in practice.

Correction Notes Are Gone, and Buyers Have Few Options

The abolition of traditional buyer correction notes has shifted the full burden of fixes onto sellers. Regardless of whether an invoice was issued inside or outside KSeF, only the seller can issue a corrective invoice. This has become a common pain point in Ministry of Finance discussions with business, where the most frequent demand is to allow buyers to correct minor formal errors themselves – or at least to initiate a correction through the system. Until such a feature arrives, every small slip forces a full correction cycle that pushes out processing and payment timelines.

Algorithmic Patches Mask Deeper Data Quality Issues

Exorigo-Upos data shows that over 7 percent of correcting invoices were sent without any systemic linking of correction lines, causing the “before” and “after” rows to get lost in the system. While an intelligent algorithm manages to automatically repair about two-thirds of those, a separate problem – incomplete XML files – affects about 10 percent of all correction invoices. In 3.5 percent of cases, the unit price is missing; in 2.5 percent, the total position value is absent. These gaps force IT systems to calculate missing data on the fly, and a KSeF acceptance number does not guarantee the invoice is fit for automated processing.

Underneath these technical shortcomings lies a behavioural gap. Many businesses continue to issue invoices outside KSeF out of habit, then later supplement or cancel them inside the system – afraid, as Sosnowski puts it, “to leave the beaten track and the structures they have built.” That dual-track behaviour generates further inconsistencies and makes automatic document exchange with counterparties unreliable.

What Finance Teams Should Do Differently

Finance and accounting leaders dealing with KSeF implementation can take several concrete steps drawn from the patterns experts are observing:

• Validate XML completeness before sending. Check that unit prices, total position values and line-item linkages are populated. The 10% incomplete-file rate on corrections – especially the 3.5% missing unit price and 2.5% missing total value – can be eliminated with a pre-send checklist integrated into your ERP or invoicing tool.
• Build duplicate detection into the invoicing workflow. Double invoices for the same counterparty, a common human error highlighted by Joanna Łuksza of IFIRMA, can be caught by a simple same-day same-counterparty alert before the factura hits KSeF and forces a correction cycle.
• Retrain teams to think in XML, not PDF. Stress that a KSeF number does not mean the invoice is error-free. Every discrepancy between the visualisation and the XML slows the buyer’s process and exposes both parties to the double-VAT risk. Include real examples from your own organisation in training sessions.
• Monitor Finance Ministry discussions on buyer-initiated correction tools. If buyers are eventually allowed to correct minor formal errors or at least flag them through the system, your receivables and payables processes will need updating. Assign a team member to follow the ministry’s business consultations.
• Measure your internal correction rate and link it to payment cycle time. Track what proportion of your KSeF correction invoices contains incompleteness or linking errors, and compare the average payment delay on those invoices versus clean ones. That metric will make the business case for tightening your front-end controls.