For years, KSeF (the National e-Invoicing System) was the project that was supposed to come into force “any minute now,” yet it continually failed to do so. There were cancellations, postponed deadlines, industry protests, an audit that revealed critical system errors, and further consultations. When the system finally launched – on 1 February 2026 for the largest companies, and on 1 April for the rest – part of the market was ready. Another part had hoped the deadline would be delayed yet again. And it is precisely these companies that are facing the biggest problems today.
The numbers look impressive. On 30 March 2026, the Ministry of Finance boasted that 87 million invoices had already been issued since the system’s launch. February alone saw over 35 million invoices issued by more than 152,000 entities – over six times more than in the entire voluntary KSeF period since 2022. It sounds like a success. However, behind these figures lies a reality that companies are grappling with daily, and which no one is talking about out loud. After the first month of the system’s operation, entrepreneurs are raising the alarm about organisational chaos, authorisation issues, and the double booking of invoices. KSeF has proven to be much more than a technical change. It has become an organisational stress test for Polish business. And, as the first weeks of mandatory e-invoicing show, the results of this test are highly instructive.
KSeF and the Accounting Firm: Who is Responsible for Issuing the Invoice?
If there is one mistake that has repeated itself most frequently in the first weeks of mandatory KSeF, it is this one. An entrepreneur hears “KSeF is mandatory,” and their first thought is the same as with any new tax obligation: let’s hand it over to the accountants.
The problem is that, this time, it does not work automatically. An accounting firm can issue invoices in KSeF on behalf of a client, but only if the entrepreneur personally grants them the appropriate authorisations within the system. The firm cannot grant itself access. Furthermore, regardless of who technically issues the invoice, the accounting firm does not know what you sold, to whom, when, and for how much – and without this operational knowledge, they cannot issue the initial invoice. Massive information campaigns have led some entrepreneurs to the false belief that the entire migration to KSeF can simply be delegated to their accountants. In reality, the first and crucial step – granting access and providing transaction details – always lies with the entrepreneur.
An accounting firm cannot perform tasks for which it has neither the access nor the knowledge of the client’s transactions. It is this lack of a clear division of responsibilities that is becoming a growing source of misunderstanding between entrepreneurs and their accountants.
No KSeF Penalties in 2026: Does That Mean You Can Wait?
Some companies deliberately delayed their integration, assuming that since there would be no severe financial penalties for errors in the initial period, there was no need to rush. These taxpayers acted entirely rationally, as the vast majority continue to issue paper and electronic invoices the old way, while a small fraction does it twice: the old way and via KSeF. Moreover, some taxpayers did this completely unknowingly, as general knowledge about KSeF remains minimal. When asked about KSeF invoices, many suppliers or service providers reply that they “heard something about it” but “won’t be dealing with it right now.”
While KSeF may not generate sanctions during the transition period, organisational errors do not simply vanish. Every month spent without proper procedures in place brings an increased risk of an incorrect document flow, double booking, and discrepancies that may later require explanation before the tax authorities.
Double Booking of KSeF Invoices: How It Happens and How to Avoid It
This is one of the most surprising problems of the first few weeks, and simultaneously one of the most costly. Document duplication is a major challenge – this occurs when the same invoice reaches the company both through KSeF and via email, which can lead to an overstated VAT deduction or double payment. Purchasing department staff, unaware of the invoice residing in KSeF, log the document from their email, while the accounting department downloads it from the government platform. The company ends up with two invoices for the exact same transaction, and suddenly, the same cost appears twice in the VAT return.
For invoices subject to KSeF, the invoice within the system becomes the official reference document, whereas a PDF or printout can only serve as a visualisation displaying a QR code once the KSeF number has been assigned. In other words, for KSeF-mandated invoices, the structured invoice sent to the system is what legally matters; the PDF or printout should merely be treated as its visual representation.
Dates in KSeF: Why the Order Has Legal Significance
KSeF brings an end to one of the most deeply ingrained habits in Polish business. For years, the end of the month often meant a flurry of post-dated corrections, adjustments, and the tidying up of invoices. The paper system, or classic electronic document flow, offered a certain degree of flexibility here. Under KSeF, this flexibility is significantly reduced, because the exact moment an invoice is successfully uploaded to the system and assigned a KSeF number is what matters. In practice, this means that not only does the date written on the invoice carry weight, but also the precise moment it was successfully transmitted to KSeF and given its identifying number.
Discrepancies between the date of sale, the date of issue, the date of transmission to KSeF, and the date it is recorded in the VAT register could trigger questions from the tax authorities. Therefore, the sequence of actions, document approval, and the timely transmission of invoices to KSeF must be clearly outlined in internal procedures.
Tax Audits and KSeF: What Will the Tax Office Look Out For?
KSeF will increase the transparency of invoice circulation. Consequently, during verification procedures or audits, the tax authorities will be able to easily cross-reference invoice data with VAT registers, JPK (SAF-T) files, and accounting documentation. Particular scrutiny will be placed on the accuracy of contractor data, invoice issue and receipt dates, VAT rates, the handling of credit notes (corrections), duplicate control, and the scope of authorisations granted to employees or the accounting firm. In practice, not every verification will immediately turn into a full-scale tax audit. Often, the first stage will involve preliminary verification activities, during which the authority will ask for an explanation of discrepancies between the invoices, JPK files, VAT registers, and accounting records.
It is worth noting, however, that 2026 is a transitional period. The Ministry of Finance has indicated that no fines will be levied for errors related to KSeF usage during this time, with sanctions only set to apply from 1 January 2027. However, this does not mean companies should put off their preparations. This penalty-free period should be used to get procedures in order, because once it ends, discrepancies in invoices, corrections, authorisations, or VAT settlements will be much more easily detected by the tax authorities.
How to Adapt Your Company to KSeF and Avoid VAT Risks
The first months of KSeF’s operation show that merely implementing the system does not conclude the organisation’s adaptation process; rather, it often merely begins it. Companies that considered themselves ready simply because they could technically send invoices to the Ministry of Finance’s system are increasingly realising that this was only step one. Safe usage of KSeF does not start with technical integration, but with streamlining the document flow, implementing access controls, eliminating duplicates, and establishing a clear procedure for handling corrections.
For more information about KSeF, please visit the official Ministry of Finance website: https://ksef.podatki.gov.pl/
If you would like to assess whether the processes implemented in your organisation comply with KSeF requirements and do not generate tax settlement risks, please feel free to contact us. We can help verify your current solutions, identify potential risk areas, and prepare your company to operate safely within the KSeF environment.
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