KSeF (Krajowy System e-Faktur) is a centralized ICT platform introduced by the Polish Ministry of Finance. Its primary objective is to standardize, streamline, and strengthen the circulation of invoices in Poland. The e-invoicing system is one of the key elements of the digital transformation of tax settlements and VAT control in Poland, aiming to improve transparency and efficiency in the Polish tax system.
What Is KSeF and How Does the National e-Invoicing System Work in Poland?
The National e-Invoicing System (KSeF) is a nationwide ICT system operated by the Head of the National Revenue Administration (KAS), who acts as the data controller. The system functions as a central platform for managing structured electronic invoices in Poland.
KSeF is primarily used for issuing, receiving, storing, and reviewing structured invoices, commonly referred to as e-invoices. Each document submitted to the KSeF system is automatically assigned a unique identification number, known as the KSeF number, which allows the invoice to be clearly identified within the Polish tax system.
The system is based on an authorization and authentication model, meaning that access to documents and the ability to issue e-invoices require prior authentication and appropriate user permissions. KSeF ensures a high level of data security and integrity, guaranteeing that the content of invoices stored in the system cannot be altered.
Mandatory KSeF from 1 February 2026 – What Does It Mean for Businesses and Taxpayers in Poland?
The introduction of mandatory KSeF will take place in stages, starting on 1 February 2026 for the largest businesses whose annual sales exceeded PLN 200 million in 2024. All other taxpayers operating in Poland will be covered by the obligation from 1 April 2026.
It should be emphasized, however, that the obligation to receive invoices via the KSeF system will apply to all taxpayers as of 1 February 2026. The legal form of the business is irrelevant – the system will apply both to companies and to sole proprietors conducting business activity in Poland.
By the end of 2026, certain transitional relief measures are provided for smaller entities. Businesses whose monthly gross sales do not exceed PLN 10,000 will be allowed to issue paper or electronic invoices instead of structured e-invoices via KSeF.
E-Invoices in KSeF: Rules for Issuing Invoices and Document Flow Within the System
A structured invoice is issued in electronic form and recorded in XML format, in accordance with a predefined template (schema) specified for the Polish National e-Invoicing System.
The process begins either in the company’s financial and accounting system or in the free tools provided by the Polish Ministry of Finance, where the issuer completes the invoice data. After user authentication, the document is transmitted to KSeF, where the system verifies its compliance with the required logical structure as well as the issuer’s authorization. Once the verification is successful, the invoice is assigned a KSeF number and is automatically made available to the buyer.
The issuance of the invoice is confirmed by an Official Receipt Confirmation (UPO – Official Acknowledgement of Receipt), which includes, among other information, the date on which the document was accepted by the KSeF system.
KSeF 2.0 – Changes, Implementation, and Current Guidelines of the Polish Ministry of Finance
KSeF version 2.0 introduces a new logical structure for e-invoices, designated as FA(3), which will replace the current FA(2) structure as of 1 February 2026.
One of the key new features of the FA(3) structure is the “Attachment” element, which enables the transmission of additional data together with the invoice. The use of this functionality requires prior notification to the Polish tax office. It is important to note that the KSeF system will not accept attachments in the form of separate files, such as PDF or JPG documents.
On 28 January 2026, the Polish Ministry of Finance made the KSeF 2.0 production API environment available. Further system development is also planned, including integration with the national digital identity hub, which will facilitate user authentication, for example via the mObywatel application.
KSeF Taxpayer Application – How to Use the Platform and What Is the Taxpayer App Designed For?
The KSeF Taxpayer Application is a free, browser-based tool provided by the Polish Ministry of Finance, intended primarily for entities that do not use commercial accounting software. The platform enables users to issue, receive, and review structured e-invoices, as well as to manage user authorizations and generate KSeF tokens and certificates.
The application is not intended for maintaining accounting records and does not store a database of business partners, although it integrates with the Statistics Poland (GUS) API to retrieve buyer data.
The production version of the application adapted to KSeF 2.0 will be made available on 1 February 2026.
Issuing and Receiving Invoices in KSeF vs. Invoices Outside KSeF – Key Differences and Obligations in Poland
The primary difference lies in the format – invoices issued within KSeF are structured XML files, whereas invoices issued outside the system may be paper-based or electronic, for example in PDF format.
Invoices issued to consumers (B2C) remain optional within KSeF. If the seller submits such invoices to the system, they must ensure that the buyer has access to the invoice, for example through a visual representation containing a QR code.
Invoices issued under special VAT procedures (e.g. OSS, IOSS) as well as tickets serving as invoices are also excluded from the obligation to be issued via the KSeF system.
Invoices received from foreign suppliers are not subject to reporting in KSeF.
It is also worth noting that e-invoices are archived in the KSeF system for 10 years, which relieves taxpayers in Poland of the obligation to store them independently.
Self-Billing in KSeF – What Does It Involve and Who Does It Apply To?
Self-billing in KSeF involves the issuance of an invoice by the buyer on behalf of and in the name of the seller.
In such cases, the unique KSeF number will contain the buyer’s tax identification number instead of the seller’s Polish tax identification number (NIP). This procedure may apply to domestic transactions as well as to intra-Community supplies of goods (ICS).
Buyers from the European Union, identified by an EU VAT number, may voluntarily issue structured invoices under the self-billing procedure, even if they do not hold a Polish NIP. In order for an external entity to issue invoices in this mode, it must be granted the appropriate authorizations by the taxpayer within the KSeF system.
KSeF and Company Finances – Does the System Affect Settlements, Cash Flow, and Accounting Processes in Poland?
The implementation of KSeF brings tangible financial benefits, such as a reduction in the VAT refund period in Poland from 60 to 40 days. The system enables the automation of accounting processes through the direct import of purchase data, eliminating errors resulting from manual data entry.
However, businesses should conduct an internal audit of their invoicing processes in order to define the new document workflow and clearly determine the scope of responsibilities of employees and external accounting firms. It may also be necessary to review and amend contractual provisions and internal policies to align them with the realities of mandatory e-invoicing in Poland.
From 1 February 2026 to 1 January 2027 – The Practical Timeline for the Implementation of KSeF in Poland
The implementation schedule for KSeF is strictly defined:
- 1 February 2026
The start of mandatory invoice issuance for large enterprises (annual sales exceeding PLN 200 million in 2024) and the obligation to receive e-invoices for all taxpayers operating in Poland. - 1 April 2026
KSeF becomes mandatory for all remaining taxpayers with respect to issuing invoices. - By the end of 2026
Transitional periods apply to small-value invoices (up to PLN 10,000 per month) and receipts with a NIP up to PLN 450. - 1 January 2027
The end of exemptions for small receipts with a NIP, the introduction of penalties for failure to apply KSeF, and the obligation to include the KSeF number in B2B and MPP (split payment mechanism) transactions.
Which Processes Will KSeF Replace and How Will the Taxpayer’s Scope of Obligations Change in Poland?
KSeF eliminates the need to issue corrective notes and duplicate invoices, as original invoices are always available within the system.
The informal concept of “invoice cancellation” will also disappear – every e-invoice submitted to KSeF enters the formal legal circulation and any errors must be corrected by issuing a corrective invoice.
Taxpayers will assume a new obligation to include the KSeF number in JPK_VAT records as well as in payment references.
In emergency situations, special modes (offline24 and emergency mode) are provided to ensure the continuity of sales, provided that the documents are subsequently submitted to the KSeF system. Access to invoices may be granted to accounting firms without granting them authorization to issue invoices on behalf of the taxpayer.
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