KSEF – when will it arrive and what does it mean for the entrepreneurs?

The introduction of a mandatory National e-Invoicing System (KSeF) in Poland is generating a lot of interest among entrepreneurs. When will the system come into effect? What are the benefits of its use? In this article, we answer these and other questions so that you can prepare your company for the upcoming changes.

National e-Invoicing System (KSeF) – basic information

What is the mandatory KSeF system and how does it work? The National e-Invoice System (KSeF obligatory) is a system that aims to simplify and systematise the invoicing process in Poland. With KSeF, each invoice issued by taxpayers will be sent directly to a central database, which will record and verify it.

The KSeF system allows invoices to be issued and sent in XML format. This format allows data to be automatically processed and sent to the KSeF system, making the invoicing process more efficient and less error-prone.

The system was originally due to come into force in 2024, but there has been a postponement of the KSeF deadline. It is only from 1 April 2026 that mandatory e-invoicing will become standard for all KSeF taxpayers. The KSeF taxpayer system requires every invoice, including consumer invoices, to be issued in accordance with the new rules and uploaded to the system. KSeF applies to invoices issued both domestically and internationally, ensuring faster workflow and full compliance with the legislation.

Sending an invoice through the system is automated, which speeds up the entire process, reducing the risk of errors. It is worth mentioning that the domestic KSeF system brings many benefits for both entrepreneurs and the tax administration. What are the most important of these?

• Simplification of invoicing processes – the system allows for quick and easy issuing of electronic invoices, which speeds up the entire process.
• Reducing the risk of errors – the automatic transfer of data to the system allows manual errors to be eliminated.
• Reduced tax fraud – thanks to central invoice verification, the system makes it more difficult to falsify documents.
• Faster invoice verification – structured invoices are immediately sent to the central database, speeding up the invoice verification process.
• More efficient document circulation – the electronic system allows invoices to be quickly uploaded and archived, which improves document circulation within the company.

Mandatory use of the KSeF

From when will KSeF be mandatory? Mandatory w-invoicing in the KSeF system in Poland has been scheduled for the beginning of 2026. Initially, the date for the introduction of mandatory KSeF was set for 1 July 2024, but after audits of the system, the Ministry of Finance decided to postpone this date to 2026.

In the first phase, the mandatory use of KSeF will apply to entrepreneurs with annual sales of more than PLN 200 million, and in the following months the system will also come into force for other companies.

By the end of 2025, entrepreneurs will be able to use the National e-Invoice System on a voluntary basis. This is an excellent opportunity to start implementing the system in your company and gain experience in using e-invoicing before it becomes mandatory to issue invoices in the KSeF system. The implementation of the KSeF system involves adaptation to the new regulations, as well as investment in the right tools and technology.

Once the KSeF system is mandatory, taxpayers who do not use the system may face penalties. Businesses that do not implement the KSeF system may face fines or other financial sanctions.

KSeF implementation and functionalities

The implementation of the KSeF system allows businesses to issue structured invoices in XML format, which is an important part of the KSeF obligations. In line with the obligation to issue e-invoices, every sales invoice must be uploaded to the KSeF system. The system allows electronic structured invoices to be easily uploaded and archived, simplifying workflow and ensuring compliance.

A special KSeF Mobile App will also be available to support businesses in issuing structured invoices. With this app, it is possible to quickly create, send and check the status of invoices, making it much easier to use the KSeF system in day-to-day business.

In the event of a failure of the KSeF system, entrepreneurs can issue offline invoices, which must be uploaded to the database once the system is restored. It is important that structured invoices issued offline are transferred to the system as soon as possible to comply with KSeF obligations. In the lives of businesses, mandatory KSeF has been implemented and businesses need to adapt their processes to meet the requirements of this system.

Importantly, each invoice structured with a number assigned by the KSeF system is given a unique identifier, which allows for easy verification by the tax administration. In addition, the KSeF taxpayer is obliged to send structured invoices to the system, which facilitates faster document circulation in companies.

However, it is worth mentioning that not all invoices have to be sent to the KSeF system. There are exceptions, such as invoices for intra-Community transactions or sales to consumers, which are not subject to the e-invoicing obligation. For businesses, the use of KSeF applies to almost all sales invoices. Furthermore, due to the postponement of the KSeF deadline, businesses have until 1 April 2026 to fully comply with the new rules.

Regulation and supervision of KSeF

An amendment to the VAT Act introduces mandatory e-invoicing for taxpayers, which means that from the moment it is implemented, businesses will be required to send sales invoices to the KSeF system. The life of the compulsory KSeF changes the way businesses issue and send invoices, and the compulsory KSeF has been established to improve the process of verifying companies’ turnover and reduce the risk of tax fraud.

The Ministry of Finance plays a key role in the implementation of the KSeF system, overseeing its operation and providing support to taxpayers. The KSeF is required to be used by taxpayers to upload invoices issued, allowing faster verification of company turnover and ensuring compliance.

During the consultation, entrepreneurs shared their opinions on the KSeF system. Most highlighted the convenience of using e-invoicing, but also the need to adapt the software to the new regulations. It is worth noting, however, that due to the postponement of the KSeF deadline, entrepreneurs have gained additional time to fully implement the system, allowing them to adapt their software and procedures to the new requirements.

KSeF in an international context

In the international context, KSeF is in line with EU regulations, particularly the ViDA (VAT in the Digital Age) initiative, which aims to simplify e-invoicing in the EU. The KSeF system supports mandatory e-invoicing by enabling the exchange of sales invoices in a structured format. With the implementation of KSeF, Poland is becoming part of the European trend of digitalising invoicing.

At the same time, Poland is discussing the integration of KSeF with the Electronic Invoicing Platform (PEF), which will enable the exchange of data on invoices issued with other EU Member States.

Preparation for the use of KSeF

In order to use the National e-Invoicing System (KSeF) effectively, businesses need to be familiar with the invoicing rules required by the mandatory KSeF system. It is crucial that VAT taxpayers know how to correctly send sales invoices to the system, as well as how to issue consumer invoices.

Micro-entrepreneurs can use the e-microfirma application, which provides support for handling VAT invoices and allows easier issuing of paper and electronic invoices. It is important that corrective invoices are issued in accordance with the system’s requirements. Remember that the KSeF number assigned to each invoice is crucial for sending invoices and storing structured invoices in the system.

Under the amended VAT Act, KSeF applies to invoices issued by all VAT taxpayers who must send their invoices to the system. The entry of KSeF invoices into the National Tax Administration (KAS) system is intended to simplify the invoice circulation process and speed up the verification of companies’ turnover. For this reason, KSeF taxpayers are required to use the system to issue invoices, both regular and structured invoices.

Entrepreneurs also need to bear in mind that the issuing of invoices remains in line with the current rules, but now takes place exclusively in the KSeF system to eliminate documentation errors. When receiving structured invoices, entrepreneurs are required to archive them and process them in the system.

KSeF applies to the issuing of invoices and businesses should regularly upload structured invoices into the system to comply with all the requirements of the VAT Act. An important deadline is 1 February 2026, when the mandatory KSeF is introduced on a full scale. KSeF taxpayers are also required to send corrective invoices when necessary.

Remember that from 1 February 2026, every taxpayer who issues invoices will be obliged to send them to the KSeF system, and the possibility to issue invoices in paper or traditional format will be limited. KSeF applies to invoices issued to other businesses, as well as invoices to consumers.