As of now, January 2025, the National e-Invoice System is a voluntary solution: this means that any taxpayer can issue structured invoices, but can also stay with traditional sales documents. And although for a long time – since January 2022 – entrepreneurs were assured that KSeF would become mandatory as early as July 1, 2024, nothing of the sort happened. Finance Minister Andrew Domanski officially announced on January 19, 2024, that the obligation to use the National e-Invoicing System will not go into effect in July or at all in 2024.
Since then, a lot has happened around the System. The Ministry conducted an audit, analyzed the results, organized public consultations, decided to rebuild the KSeF architecture and made many key decisions. The result of all these activities is the current – and probably already inviolable – date for the mandatory National e-Invoice System to come into force. These are February 1, 2026 and April 1, 2026.
On the former date, the KSeF will become mandatory for large entities, i.e. companies whose revenue in 2025 will exceed PLN 200 million. Two months later, KSeF will have to be used by all other taxpayers. What exactly is the National e-Invoicing System and how will the lives of entrepreneurs change after its introduction? You can find the answer below.
What is the National e-Invoicing System all about?
The National e-Invoice System is a solution designed to allow taxpayers to issue and share structured invoices in place of paper or electronic invoices. A structured invoice issued in KSeF takes the .xml format. This format – as of today – must comply with the logical structure of the FA(2) e-invoice. Why as of today? Because as a result of public consultations, the Ministry of Finance has decided that the logical structure must be updated. The FA(3) structure is expected to come into effect in parallel with the launch of the mandatory KSeF, i.e. on February 1, 2026.
Who can use the KSeF?
In principle, structured invoices in the National e-Invoice System can be issued by almost any business:
- active VAT taxpayers;
- VAT-exempt entrepreneurs;
- Taxpayers identified in Poland for the special EU OSS procedure who have a Polish TIN.
Let’s make it clear: if your company is already ready to adopt KSeF, it can use the System now. All necessary applications – including the KSeF Mobile Application – have already been made available in the production version. This means that entrepreneurs can use them and issue structured invoices without any obstacles.
However, it should be borne in mind that some of the components of the National e-Invoicing System and the legal acts related to its operation (such as the VAT Act) will change in the coming months – in February 2026 at the latest.
How to issue an e-invoice in KSeF in 2025?
A taxpayer can issue a structured invoice using KSeF’s free tools – both the trial, pre-production and production versions of the KSeF Taxpayer Application are currently available. You can access them, as well as the KSeF Mobile Application (note: the latter is only available in the production version) by clicking on this link.
Important!
If you want to see how the KSeF Taxpayer Application works, test its functions, choose the trial version. You can also use a pre-production (demo) version of the application.
If you choose the production version of the Taxpayer Application and issue an invoice in it, it will become a document entered into legal circulation. The production version is therefore the final one. It is already being used by companies that have decided to implement and launch KSeF. Once the mandatory use of the system is in place, all taxpayers will be able to use the KSeF Taxpayer Application to issue structured invoices.
After selecting the appropriate variant of the application, enter your company’s TIN, and then log in with your Trusted Profile or Qualified Certificate.
The next step will be to sign the document with an electronic signature – this will authorize it, and the KSeF system will become available to the taxpayer from now on.
Structure of the e-invoice in KSeF
Before you decide to issue an e-invoice in the KSeF system, remember that the document schema contains three types of fields to be filled in. These are mandatory, optional and optional fields. There are more than 300 fields available in the schema, so we recommend extreme caution and meticulousness, especially when issuing a structured invoice in the National e-Invoice System for the first time.
- The mandatory fields of the e-invoice must be completed regardless of the circumstances. This category includes such information as the data of the seller and buyer, the date of issuance of the document or the date of performance of the service (delivery of goods).
In the context of KSeF, it is worth remembering that negative indications, i.e. information that a circumstance does not exist, should also be introduced in the e-invoice. A value of 1 indicates the presence, while a value of 2 indicates the absence of the circumstance.
In the case of paper invoicing, such action is not required, but in KSeF it is a necessity. Nonetheless, it is expected that this obligation will be reflected in the functionality of the KSeF Taxpayer Application, and it will not be possible to omit such a field when issuing an e-invoice. Importantly, without filling in the mandatory fields, KSeF will not allow the invoice to be sent.
- Optional fields are mandatory to be filled in if a statutory condition is met, i.e. circumstances require it – e.g. the type of invoice issued, or one of the statutory conditions requiring the field to be filled in is met.
It is worth remembering that failure to fill in any of the optional fields is not a technical error, which means that the invoice will be accepted by the system and issued correctly.
However, when this invoice is received by the counterparty and an irregularity is noticed, or the invoice is audited, a corresponding correction will have to be made.
Before sending an e-invoice, review all available fields – especially optional fields – to make sure they need to be filled in.
EXAMPLE
Field P_8B – quantity (number) of goods or range of services – is optional. However, the VAT Law clearly states that it is mandatory for all sales documents except simplified invoices (documenting transactions concluded for up to PLN 450).
It is for this reason that this field has not been marked as mandatory in the system, but failure to fill it out in a standard invoice is tantamount to making a factual error and requires correction.
- Optional fields can be filled in, but this does not in any way affect the correctness of the issued e-invoice. This group of fields includes annotation fields, as well as fields that are not required to be filled in under the VAT Act, but – for example – under other laws. Thus, it may happen that the field – although optional – in the case of a given invoice actually turns out to be mandatory.
National e-Invoicing System – from when will it be mandatory?
The National e-Invoicing System was launched on January 1, 2022. – However, until now, taxpayers are not obliged to use it. Initially, KSeF was to become mandatory in July 2024, but currently (as of January 2024) we do not know the launch date for all taxpayers.
In a release summarizing the KSeF audit, Minister Domanski explained the reasons for the postponement this way:
The KSeF system is crucial to the security of economic transactions. Back in December 2023, my predecessors assured me that the system was ready for implementation on July 1, 2024. However, the decision to conduct an audit turned out to be the right one. The test report contains several hundred detailed bug reports, comments and recommendations for the architecture, source codes and database.
Andrzej Domanski, Minister of Finance
The same communiqué stated the implementation date for KSeF. It’s official from now on: The National e-Invoicing System will become mandatory:
- February 1, 2026 – for entities with revenue of more than PLN 200 million in the previous fiscal year,
- April 1, 2026 – for other companies.
It is worth emphasizing again: the National e-Invoicing System will not be mandatorily introduced in 2025.
Why hasn’t KSeF been introduced in 2024?
According to Marcin Baj, a tax advisor at LTCA, the capacity of the system as found at the beginning of 2024 was not sufficient. Under these circumstances, Polish entrepreneurs could be put in a situation where they would not be able to issue invoices while being legally obliged to do so.
The next step, after a strong response from the MF, is to commission and conduct an external audit, which is expected to result in a full list of KSeF’s errors and problems. Only after the results of the inspection will it be possible to establish an action plan and an estimated date for implementing the system.
Based on the audit results, we decided to build the system architecture from scratch. The contractor will appoint a team of IT architecture specialists. The work we will carry out will make the system reliable, safe and more functional.
Marcin Loboda, head of the National Tax Administration
For more detailed information, see the official announcement from the Ministry of Finance.
SME spokesman triumphs
For many weeks now, voices have been heard saying that businesses are largely not ready to adopt the National e-Invoicing System. One of the more high-profile ones was the initiative of Poland’s SME ombudsman, Adam Abramowicz, who sent an open letter to the Finance Minister, calling for the introduction of KSeF to be staggered.
We already know that the timetable proposed by Abramovich was not adopted, but the SME spokesman’s main point has been met. We will wait until 2026 for the mandatory KSeF, which is even a bit longer than the SME spokesman had anticipated in his plan.
What does the introduction of the mandatory use of the National e-Invoicing System mean?
Although the preparation period is well under way as of early 2022, still many companies are not ready to implement the system. Moreover, it is speculated that this is the vast majority of Polish entrepreneurs, especially small and micro businesses. Implementing KSeF is a complicated process that requires not only commitment and time, but also the resources needed to purchase the appropriate software or train employees.
By extending the deadline for making KSeF mandatory, businesses have been given valuable time to plan work and implement the system at a leisurely pace. On the other hand, it is also important to remember the large entities that have already prepared for KSeF implementation, often spending a lot of money.
The ongoing test period from 2022, but also the public consultation conducted in 2024 and the audit that preceded it, have already revealed quite a number of potential problems and ambiguities that the National e-Invoicing System may cause. Which are the most common ones that people who have already had the opportunity to use KSeF point to?
- Invoice verification – making a mistake or errors in an e-invoice can result in the KSeF system rejecting the document. This is especially important when a company sends parcels of invoices. In such an arrangement, even a seemingly trivial mistake can result in the rejection of the entire package of documents.
What’s more, once a structured invoice is sent, once it enters the KSeF system, it cannot be canceled or withdrawn – it will absolutely go for verification. This is why verification of documents before they are sent will become even more crucial than it is today. - Authorizations – many companies will have to decide to give authorizations for KSeF operations to the appropriate people – accountants, administrative staff, etc. In large entities, this will require a well-thought-out strategy.
In the context of inevitable personnel changes over months or years, it will also be necessary to attach the question of authority in KSeF to the procedure for revoking access for those leaving the company. However, the issue of privilege management has been addressed and it is already possible to manage privileges in the KSeF Taxpayer Application. - More data – structured invoices will be able to contain more details. This is due, among other things, to the fact that the European Commission accepted the Finance Ministry’s proposal in its entirety, without its own suggestions or amendments.
This means that all of the MF’s ideas have been adopted, so it may be necessary to fill out invoices in more detail. However, this is not a foregone conclusion, but a safe starting point for the legislature.
Obligation to use KSeF – exceptions during the transition period
From February 1 to July 31, 2026, the Ministry of Finance plans to launch a transition period during which taxpayers will not be required to show the KSeF number of an invoice in sales records.
Besides, the MF’s assumptions included leaving entrepreneurs a 6-month protection period, during which the contractual penalties provided for failure to comply with obligations arising from the KSeF’s entry into force would not be executed. However, at present – January 2025 – there is no official confirmation from the ministry.
However, we know that the Ministry wants to reduce penalty rates for non-compliance with KSeF obligations during the initial period. It seems, therefore, that the earlier idea, involving the complete abandonment of the imposition of penalties during the transition period, has been abandoned. However, we still have to wait for concrete information in this regard.
Benefits of KSeF
Despite the problems with the implementation of KSeF and the fact that the current technical state of the system does not allow for its full-scale launch, the Finance Ministry insists that KSeF is needed by Poland and Polish entrepreneurs. The Finance Minister made a clear statement in this regard: “We cannot allow companies to not be able to issue invoices. We cannot allow the situation that was with the Polish order. KSeF is needed for the Polish economy and will be introduced. We need to computerize the economy“.
Although, for obvious reasons, the introduction of the National e-Invoicing System (and especially the prospect of making it mandatory) raises doubts and provokes questions about problems, the system undoubtedly also brings benefits. So how will taxpayers’ lives improve after the introduction of KSeF?
- Ultimately, the system will cover all VAT payers and allow automatic generation of tax returns without filling out a PIT. This means that tax refunds should happen faster, all of which will save taxpayers time and hassle.
- The National e-Invoice System database will allow us to select the recipient of the invoice and give us confidence that the document will go to the right entity.
- KSeF is aligned with standards in the European Union – all invoices structured in the EU are created according to a single template, which will make it easier to invoice foreign contractors.
- The uniform file format (.xml) will also avoid problems related to the reading of electronic invoices by individual entrepreneurs – the standardization of the format will ensure that any company computer can cope with reading the data.
- The e-invoices created in KSeF will be stored in the cloud and protected by data backup. Such invoices cannot get lost or destroyed – so the need to issue duplicate invoices will disappear over time.
Summary
The launch of the National e-Invoice System in the Polish tax system is quite a revolution, with as many opportunities as threats. The testing period for the application, as well as a multi-stage consultation with entrepreneurs, has already ended. So work is currently underway to provide a solution that allows all businesses to issue structured invoices without hindrance.
However, any entrepreneur can already use the applications provided by the Ministry of Finance. We are talking about the KSeF Taxpayer Application, the e-microfirma application and the KSeF Mobile Application. However, it is worth noting that the available production versions are fully functional applications, the use of which involves the use of the National e-Invoice System. A document issued in the production version of the KSeF Taxpayer Application is binding and goes into the System. Test versions can be used for testing purposes. All variants of the application are available at this address.
