Did you know that the National e-Invoicing System (KSeF) will soon completely change the way invoicing is carried out in Poland? From February 2026, this system will become mandatory for large enterprises, and from April for all remaining entrepreneurs. Read our article to find out: KSeF – when does it become mandatory?
From this article you will learn:
- National e-Invoicing System – what is it?
- Advantages of a central invoicing system
- KSeF – when does it become mandatory? Implementation schedule for different groups of entrepreneurs
- Summary
National e-Invoicing System – what is it?
The National e-Invoicing System is a modern solution introduced by the Ministry of Finance that changes the way entrepreneurs issue and receive invoices. The system operates as a state-run platform for the digital circulation of financial documents, enabling the issuance, transmission, receipt, and storage of invoices in electronic form. Each invoice entered into the system is assigned a unique identification number, ensuring its authenticity and immutability.
The central invoicing system represents an important step toward the full digitalization of accounting processes in Poland. In practice, KSeF functions as a kind of database of structured invoices that are stored for 10 years from the end of the year in which they were issued. Importantly, documents submitted via KSeF are automatically verified for formal correctness, which significantly reduces the risk of errors.
The system allows access to invoices in several ways: through integrated accounting software (API), free tools provided by the Ministry of Finance, a mobile application, as well as the e-Microbusiness application available in the e-Tax Office. It is worth noting that not all documents are included in KSeF—excluded documents include, among others, pro forma invoices, accounting notes, receipts, and internal documents, which will continue to function in their current form. At KR Group, we have long observed how the digitalization of accounting processes positively impacts business efficiency. What are the advantages of KSeF?
Advantages of the central invoicing system
The implementation of the National e-Invoicing System brings entrepreneurs a number of tangible benefits. First and foremost, it significantly accelerates the circulation of documents by eliminating the need for the physical delivery of invoices between counterparties. Documents are available in the system immediately after issuance, enabling faster settlements and better control over cash flow. In addition, automatic verification of the formal correctness of invoices reduces the risk of errors that could lead to tax issues.
The central invoicing system also provides significant savings related to document storage. Invoices are automatically archived in the system for 10 years, eliminating costs associated with traditional paper-based archiving. Entrepreneurs no longer have to worry about physical storage space or the risk of documents being damaged or lost. Using accounting outsourcing services can further streamline the process of adapting to the new system and maximize the benefits resulting from its implementation.
The key advantages of the National e-Invoicing System include:
- reduction of the VAT refund period from 60 to 40 days, positively impacting cash flow,
- automation of accounting processes and reduced labor intensity,
- reduction of costs related to printing and mailing paper invoices,
- minimization of the risk of documents being lost or destroyed,
- easier access to documents for authorized employees,
- greater certainty that the invoice has reached the recipient,
- standardization of invoice formats, facilitating the exchange of information between systems.
KSeF – when does it become mandatory? Implementation schedule for different groups of entrepreneurs
The question “KSeF – when does it become mandatory?” concerns many entrepreneurs. The Ministry of Finance has planned a gradual implementation of the system to allow companies sufficient time to prepare for the change. According to the schedule, the obligation to use the National e-Invoicing System varies depending on the size of the company. From 1 February 2026, KSeF will become mandatory for large enterprises whose turnover exceeded PLN 200 million (including VAT) in 2024. Other entrepreneurs will be required to use the system from 1 April 2026.
It is worth noting that although the issuance of invoices in KSeF will be introduced in stages, the receipt of invoices via this system will be mandatory for all taxpayers as of 1 February 2026, subject to exceptions provided for in the regulations. Prior to full implementation, a technical downtime is planned from 26 to 31 January 2026, related to the final transition from KSeF 1.0 to KSeF 2.0. The new KSeF 2.0 API version has been available for testing since September 2025, enabling the integration of financial and accounting systems before the obligation comes into force. Keep in mind that professional tax advisory services can prove invaluable when planning the KSeF implementation schedule in your company.
The question “KSeF – when does it become mandatory?” should also be considered in the context of transitional facilitations. Until the end of 2026, certain simplifications will apply, including the possibility of issuing invoices outside KSeF in the case of low monthly sales (up to PLN 10,000 including VAT) and the continued use of cash registers. It is also worth remembering that consumer invoices (B2C) may be issued in KSeF on a voluntary basis—the decision in this regard rests with the seller. The system also offers an offline24 mode, which allows invoices to be issued in the event of technical problems with system access, providing a safeguard for business continuity.
From 1 February 2026, it will also be possible to issue invoices with attachments, provided that the intention to issue such invoices is reported in advance via the e-Tax Office (from 1 January 2026). It should be noted that invoices entered into the National e-Invoicing System—once they are submitted—cannot be edited; in the event of an error, it is necessary to issue a corrective invoice, which constitutes a significant change compared to the current invoicing system.
Summary
You now know what the National e-Invoicing System is and when it becomes mandatory. This is a groundbreaking solution that fundamentally changes the way invoices are issued and received in Poland. As a central invoicing system, it offers numerous benefits, including faster document circulation, reduced risk of errors, and automatic archiving. The implementation schedule has been spread over time to allow entrepreneurs to prepare properly for the change. It is worth starting preparations for this transformation now in order to avoid problems when the system becomes mandatory. We encourage you to take advantage of our support in the process of implementing the National e-Invoicing System in your company.
