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National e-Invoicing System (KSeF)
The National e-Invoicing System (KSeF) is a centralised system designed for issuing, sending, receiving and storing invoices. Beginning from 1 February 2026, it will gradually become mandatory for all businesses in Poland.
The main idea behind KSeF is to fully digitalize the circulation of invoices and limit the number of ways in which they may be issued. From the moment it comes into place, invoices will, as a rule, only be considered valid and effectively delivered if they are sent and registered with the use of KSeF.
Consequences for the contractual practices of businesses
Ensuring a company’s compliance with the requirement of the universal use of the National e-Invoicing System turns out to be a task not only for finance but also for sales and purchasing departments. This is because the general change in invoicing rules will have a significant impact on the contractual practices of organisations, including, among others:
- the method of calculating the payment deadline,
- definition of the method and form of invoice delivery in the contract,
- contractual provisions setting out specific requirements for the content of an invoice,
- obligations to deliver attachments relating to an invoice and their identification.
The time of receipt of an invoice in KSeF and payment deadlines
As stated at the beginning, KSeF invoices will be considered effectively delivered as soon as they are registered in the system. Even though businesses will continue to be able to send each other documents with the content of the invoice (e.g. in PDF format), these will be just for ‘visualisation’ purposes. The invoice issued and delivered via KSeF will still be the only one that is binding and significant from the legal point of view.
The above rule considerably alters the way payment deadlines are calculated, where the time limit begins to run from the date of delivery of the invoice (e.g. ‘… payable within 14 days of delivery of a correctly issued VAT invoice to the Buyer’). This is because, beginning from 1 February 2026, the deadlines will be calculated from the date of registration of the invoice in the KSeF system, irrespective of whether or not, and when, the ‘invoice visualisation’ is delivered by other means.
Nevertheless, the method of calculating payment deadlines is not something over which the parties to the contract have no control. They can still agree on the starting point for calculating the payment deadline (e.g. the time of delivery of the ‘invoice visualisation’ or other accompanying documents). This, however, requires changes to the existing contracts and to the contract templates on the basis of which contracts will be concluded in the future.
Special contractual provisions regarding the content as well as method and form of delivery of documents relating to an invoice
Many businesses have special requirements as to the content of invoices delivered to them by their trading partners. In addition to the data specified by generally applicable laws, such invoices must also include the reference number of the contract from which the amount due arises, the purchase order numbers, or the cost centre identification.
The format of invoices issued via KSeF will still allow such data to be entered, but it will be difficult to correct them if necessary. For this reason, it becomes even more important to clearly specify in the contract what data are to be included on the invoice and whether their absence means that the invoice has been issued incorrectly, i.e. that a corrective invoice is required.
Irrespective of the content of an invoice, due to organisational requirements or the nature of the contract, it is often necessary to submit certain documents (e.g. statements, reports or confirmations) together with the invoice. Although KSeF will enable the issuance of the so-called ‘invoices with attachments’, their practical application may be limited (e.g. due to the required format of the attachment, i.e. XML). In view of this, organisations will face the challenge of specifying in more detail in the contract how exactly such attachments are to be delivered and linked to the invoice, and, very importantly, of determining the relationship between the time of delivery of the attachments and the invoice payment deadline.
In consequence, in the case of more complex requirements regarding the content of an invoice and the documentation delivered with it (which frequently determines its correctness), the parties to the contract may agree on a procedure where the content of the invoice to be issued in KSeF is agreed and approved beforehand.
Invoices for foreign trading partners
A relation with a foreign trading partner, who is not required to use KSeF, does not release a Polish business from the obligation to issue an invoice in the system. The invoice should still be generated and registered in KSeF, and the only thing that changes is the method of its delivery, as it will be delivered as a ‘visualisation’ in a manner agreed with the trading partner in the contract.
With this in mind, it is a good idea to consider including provisions in contracts with foreign partners that comprehensively describe the rules for issuing invoices in Poland and delivering their ‘visualisation’ to a trading partner. It is worth noting here that for a Polish business it is always the invoice registered in KSeF that is the binding accounting document, regardless of the content of the ‘visualisation’ delivered to a foreign partner.
Invoices issued outside the system (the so-called offline mode)
The regulations governing the National e-Invoicing System allow, under certain conditions (e.g. in the event of network problems or KSeF failure), invoices to be issued outside the system, subject to their subsequent registration in KSeF (the so-called offline mode). As in the case of contracts with foreign partners, it is advisable to consider setting out rules in the contract for the issuance and delivery of invoices in offline mode, including the determination of liability for inconsistencies between an invoice delivered outside the system and the one registered in KSeF, as well as liability for the consequences of delays in registering an invoice in KSeF after the failure has been rectified.
Adapting contract templates to the requirements of specific organisations
The areas of potential contractual arrangements proposed above are only examples of what a specific organisation may expect from the invoicing process. In order to comprehensively define the requirements of a business, it will be important for its finance and purchasing departments to cooperate in working them out.
It cannot be ruled out that, due to an organisation’s standards and the nature of contracts it enters into, no major alteration to its current contractual practices will be necessary or, quite the contrary, there will be a need for a radical change and the development of new organisational standards.
If you have any questions or concerns, or if you are simply wondering what your first step should be regarding your organisation’s contractual standards, please do not hesitate to contact us.