The National E-Invoice System (KSeF) is a very popular topic in 2025. Many businesses are looking for reliable information, as the Ministry of Finance has changed the framework for this solution several times, including postponing the effective date of the KSeF regulations. The following guide is a compendium of knowledge about the KSeF, presenting the status as of July 2025 – we invite you to read it.
What is KSeF, or the National System of e-Invoices?
KSeF is a platform prepared by the Ministry of Finance, which is used to issue and receive structured invoices electronically. Using KSeF it is possible to generate and share structured invoices (in XML format)The operation of KSeF will ensure that issued invoices will be transferred to a central database, which will increase the security of their circulation.
KSeF version 1.0 and KSeF version 2.0 – what is the difference?
In the context of KSeF, we can speak of two versions – KSeF 1.0 and KSeF 2.0. KSeF 1.0 is the initial version (test environment) that entrepreneurs currently use voluntarily.
KSeF 2.0 is a version of the National e-Invoice System that has been optimized – taking into account the comments of entrepreneurs, accounting offices, auditors and software suppliers. It will be mandatory from 2026. (details below). KSeF 2.0 differs from KSeF 1.0 in several ways, including the available methods for sending invoices.
How does KSeF work?
To issue a structured invoice, the user can use the software and API provided by the Ministry of Finance or choose a commercial solution and thus, for example, integrate the software already used with KSeF. The process of issuing structured invoices is characterized by:
- assigning a unique number to the invoice – this is a number separate from the invoice number assigned by the entrepreneur;
- issuing an official receipt certificate (UPO) – it is generated for the invoice issuer;
- authentication, which must be performed by the invoice recipient – otherwise he will not be able to view the invoice.
From when will the use of KSeF be mandatory?
The National E-Invoice System is nothing new – it's a solution that businesses can voluntarily use from the beginning of 2022. At the same time, the effective dates of the mandatory version of the KSeF have been postponed several times. Ultimately, the KSeF will be mandatory from:
- February 1, 2026 – for large entrepreneurs (entities whose sales value together with the tax amount exceeded PLN 200 million in 2024);
- April 1, 2026 – for all other entrepreneurs (except for digitally excluded entrepreneurs).
Digitally excluded entrepreneurs will be given more time to adapt to the changes being introduced – KSeF will be mandatory for them only from the beginning of 2027. This loophole is available only to the smallest entrepreneurs – in their case, the monthly sales value (including tax) documented by invoices cannot exceed PLN 10,000.
Will KSeF be mandatory for every entrepreneur?
The National e-Invoice System will be used by: entrepreneurs registered as active VAT payers, entrepreneurs exempt from VAT, and taxpayers with a Polish Tax Identification Number (NIP) and using the OSS procedure. Article 106ga, paragraph 2 of the VAT Act, provides information on when issuing invoices in the National e-Invoice System will not be mandatory.
Who is not subject to the obligation to issue structured invoices using the National e-Invoice System – examples:
- taxpayers who do not have a registered office or permanent place of business in Poland,
- taxpayers who issue invoices to the purchaser of goods or services who is a natural person not conducting business activity,
- taxpayers who benefit from the exemption when they do not exceed the turnover limit of PLN 200,000.
How does a structured invoice differ from an electronic and paper invoice?
KSeF allows for the issuance of structured invoices, which are sent electronically. However, this does not mean that structured invoices and electronic invoices are equivalent. A structured invoice is an invoice issued in XML format that has a defined logical structure.An XML format is not required for an electronic invoice – it can be sent to the customer electronically, e.g. in PDF format.
A structured invoice differs from a paper invoice in its form – the former is in electronic form, while the latter is a physical document (in paper form).The difference is also visible when it comes to archiving – in the case of paper documentation, it is more expensive and time-consuming.
Will KSeF eliminate paper invoices?
Ultimately, KSeF will result in paper invoices no longer being used in business transactions. – The National e-Invoice System will force a nationwide transition to electronic invoicing. At the same time, not every transaction will need to be documented with a structured invoice – examples of exceptions include:
- invoices issued to consumers,
- single tickets that drivers receive when using toll road sections,
- invoices issued by taxpayers who use the non-EU OSS or IOSS procedure.
What about invoices from cash registers?
Some entrepreneurs issue fiscal receipts daily, which are considered invoices (up to PLN 450 with the buyer's Tax Identification Number). Therefore, the Ministry of Finance has decided on a transitional period – By the end of 2026, entrepreneurs subject to the obligation to issue structured invoices will be able to issue:
- invoices in electronic form or paper invoices using cash registers,
- receipts that will be recognized as invoices.
Will it be necessary to use KSeF when cooperating with foreign companies?
Some entrepreneurs from Poland have foreign clients. Such cooperation does not exempt the entity subject to the obligation to use the National e-Invoice System from issuing a structured invoiceAt the same time, the entrepreneur will gain additional obligations – he will have to provide the invoice with a verification code (QR code) and forward it to the recipient (contractor) in the agreed form.
By marking the invoice with a QR code, the recipient will have access to it in the National Tax Administration (KSeF) and will be able to verify the data. The invoice issuer will also be obligated to provide the verification code to consumers or buyers who do not use a Tax Identification Number (NIP).
What is 24/7 offline mode?
In the KSeF 2.0 version, the online mode of issuing structured invoices will not be the only option – an offline mode will also be available. The Ministry of Finance distinguishes between two procedures – offline mode and offline mode.24 The differences between them are as follows::
- offline mode applies in the event of system unavailability - the user will be able to issue an invoice based on the template and will then have 7 business days from the removal of the failure to send the document to KSeF (unless a so-called total failure occurs, which will be announced in the media - then sending the issued invoice or invoices to KSeF will not be necessary);
- offline mode24 was created as a response to concerns raised by test mode users - this is a solution that the user will use in case of problems with the internet connection, and which involves issuing an invoice in accordance with the applicable template and sending it to KSeF no later than the next business day after its issuance.
KSeF and PEF – what is the difference?
KSeF is not the first platform supporting the trading of structured invoices. Since 2019, PEF (Electronic Invoicing Platform) has been operating in Poland – a solution enabling the transfer of structured documents between entrepreneurs and public institutionsHowever, KSeF and PEF are two distinct and unrelated systems. The differences between them are as follows:
- KSeF is a nationwide platform through which entrepreneurs can issue, send and store structured invoices – this solution is intended to replace the previously issued paper and electronic invoices in everyday economic circulation;
- PEF is a platform dedicated to public procurement – it is used by public entities placing orders and contractors.
Importantly, KSeF and PEF are not integrated with each other – documents issued on one platform will not be available on the other.
Digital certificate authentication – what are KSeF certificates?
The KSeF implementation project originally assumed authentication using tokens – after the changes, this method will be replaced by digital certificates with a validity period of 2 years. When the obligation to issue invoices via KSeF comes into force, entrepreneurs will be able to use both certificates and tokens – the latter method of authentication will no longer be available from 1 January 2027.
Businesses can apply for a KSeF certificate from November 1, 2025. A KSeF certificate will be required to mark structured invoices with a code identifying the issuer when they are issued in emergency, offline, and offline modes.24 Implementing certificate support in a company's system can be challenging for businesses (partly due to the XAdES-BES electronic signature format), so it's worth considering using a commercial solution – for example, our KSeF API.
What else is worth knowing about KSeF?
The Ministry of Finance has changed the assumptions of the KSeF many times, as a result of which contradictory information has appeared in the public space. In July 2025 it is known that:
- the KSeF invoice number will only need to be provided when making payments between active taxpayers from 2027,
- issuing VAT RR invoices and VAT RR CORRECTION invoices will be available to KSeF users only from April 1, 2026,
- Entrepreneurs using KSeF will be able to issue invoices with attachments from February 1, 2026.
What do entrepreneurs gain by using KSeF?
Although the National System of e-Invoices is not yet mandatory in 2025, entrepreneurs who decide to use the National System of e-Invoices can gain a lot. The key benefits of using KSeF are as follows::
- no need to archive invoices – this means lower costs;
- no need to issue duplicate invoices – KSeF prevents invoices from being lost;
- possibility of obtaining a tax refund in a shorter period – 40 days instead of 60 days;
- fast and automated exchange of invoices between companies – saving time;
- security – data included on the invoice in KSeF cannot be manipulated.
