Michał Wykurz

The implementation of the mandatory National e-Invoice System (KSeF 2.0) is the most significant transformation in Polish value added tax (VAT) in years. Developed and made available by the Ministry of Finance, this system revolutionizes the existing invoicing model, which relied on the direct exchange of documents between contractors. The mandatory KSeF will transform this process into a centralized public circulation system. Invoices will no longer be sent directly to the recipient, but must first be sent to a government platform, where they will be validated, authenticated, and only then made available to the purchaser. The main objectives of this change are to standardize documentation, increase the transparency of taxpayers’ activities, reduce bureaucracy, and tighten the tax system by gaining access to transaction data in real time. The obligation to use structured e-invoices requires urgent adaptation of IT systems and internal procedures for almost all businesses in Poland, constituting a key element of their VAT compliance.

Chronology of implementation and scope of obligations in 2026-2027

The option to voluntarily use KSeF has been available since January 1, 2022, but the key changes for businesses will take place in 2026-2027. The legislator will introduce the obligation to use structured invoicing in stages, with the start date depending on the size of the entity:

1. From February 1, 2026, the obligation to issue invoices in KSeF will apply to large entrepreneurs whose revenues exceeded PLN 200 million in 2024. At the same time, a uniform logical structure of the FA(3) invoice will be introduced.
2. From April 1, 2026, the obligation to issue invoices in KSeF will apply to other businesses, including SMEs and micro-enterprises (except for the smallest entities).
3. From January 1, 2027, the KSeF obligation will become full and universal, also including micro-enterprises (which will be exempt from the obligation to use KSeF until December 31, 2026, if their monthly gross turnover does not exceed PLN 10,000).

Regardless of the date of commencement of the mandatory issuance of e-invoices, in practice, every company must be technically ready to receive and process structured invoices as early as February 1, 2026 (as it may make a purchase from a large entity that will start invoicing in KSeF on the above-mentioned date).

Exceptions to the KSeF universality rule

However, it is worth noting that certain types of invoices and transactions remain outside the mandatory KSeF. In the case of consumer invoices (B2C), the seller will have the freedom to issue a structured invoice in KSeF or a paper/electronic invoice outside this system. A separate logical structure (FA_RR(1)) is provided for VAT RR invoices and VAT RR corrections – the need to issue such a structured invoice by the purchaser of agricultural products will depend on the submission of a declaration by the flat-rate farmer. When providing insurance and financial services, which Exemption from KSeF is also provided for transactions covered by cross-border self-invoicing – although in some cases structured invoices may be issued voluntarily.

How will KSeF 2.0 change tax settlements?

The introduction of the obligation to use structured invoices will affect certain aspects of VAT settlements.

Simplification for “in minus” corrections

The most significant change, beneficial to taxpayers, will be the modification of the rules for settling downward adjustments, i.e., those that reduce the tax base and VAT due. Thanks to KSeF 2.0, the current requirement to have documentation confirming the determination and fulfillment of the conditions for adjustment (the so-called Slim VAT rules) will be abolished. What does this mean?

• For the Seller – an adjustment to the tax base will be possible upon issuance of a structured corrective invoice (in practice: upon sending it to KSeF). This will eliminate delays associated with waiting for documentation to be collected, which will improve the company’s cash flow.
• For the buyer – the obligation to correct the input tax will arise in the settlement for the period in which they receive the corrective invoice via KSeF (i.e., when the corrective invoice is assigned a number in KSeF).

Faster VAT refunds

One of the benefits of KSeF 2.0 will be a reduction in the basic VAT refund period. Under the current legal framework, the basic period for refunding the excess of input VAT over output VAT to a bank account is 60 days. From February 1, 2026, with the entry into force of the obligation to use KSeF 2.0, this period will be reduced to 40 days. This change will certainly improve the financial liquidity of domestic entrepreneurs.

The moment of issuing and receiving an invoice

Another aspect related to the entry into force of the mandatory KSeF is the change in what is meant by the terms “issuing” and “receiving” an invoice. The date of issue of an invoice will generally be the same as the date it is sent to KSeF. In turn, the date of receipt of the invoice will be the date on which the invoice is assigned a number in KSeF. In practice, in almost every case, the issuance and receipt of an invoice will therefore take place on the same day.

The above issue will therefore affect the moment when:

• a VAT tax obligation arises in certain types of transactions (including construction services, supply of utilities and telecommunications services, rental, leasing, lease – i.e., cases where the tax obligation depends on the issuance of an invoice).
• the right to deduct VAT arises – receiving an invoice will no longer be linked to the physical receipt of the document, but to the assignment of a number to it in KSeF (even if the buyer does not download it from KSeF on that day and does not read its content).

What if the seller issues us an invoice outside of KSeF despite the obligation to do so?

Although KSeF tightens the system by centralizing and controlling the moment of document issuance, it does not change the fundamental principle of VAT neutrality for the buyer. Current individual interpretations indicate that a buyer who receives an invoice documenting an actual economic transaction will retain the right to deduct input tax, even if the document was issued outside KSeF, contrary to the seller’s obligation. The buyer is therefore protected. Any consequences of violating the KSeF obligation (in the form of financial penalties) will therefore only apply to the issuer of the invoice.

Offline invoicing

In the era of mandatory KSeF, the rule will be online invoicing (in real time, i.e., sending invoices to KSeF on the day they are generated). However, in the event of system unavailability or failure, entrepreneurs will have to use the so-called offline modes:

• In the event of KSeF unavailability (i.e., scheduled maintenance work, communicated in the BIP MF and in KSeF itself), it is not possible to issue invoices outside KSeF to other taxpayers using KSeF. Therefore, you should wait until the system is up and running before sending the invoice to the customer. Invoices generated while KSeF is unavailable should be sent within 1 business day after the system becomes available again.
• In the event of a KSeF failure (i.e., an unplanned, temporary shutdown of KSeF, communicated on the Ministry of Finance’s Public Information Bulletin website and in KSeF itself), invoices should be issued in a structured manner (i.e., in accordance with the logical structure of FA(3)). They can then be sent to buyers using KSeF outside the system, in a manner agreed with them. However, invoices issued during the failure period should be sent to KSeF no later than within 7 business days after its end.
• In the event of a complete failure (permanent shutdown of KSeF, announced in the mass media), taxpayers will be able to issue invoices in an unstructured manner (i.e., in paper or electronic form). There will be no obligation to send them to KSeF later.

In addition, taxpayers will be entitled to use the so-called offline mode24 at will. This mode allows structured invoices to be sent to KSeF within 1 business day of their generation at the latest. In offline mode, it is not possible to issue invoices outside KSeF to other taxpayers using KSeF. The purchaser will therefore receive the invoice only after it has been sent to KSeF.

Penalties for KSeF-related violations

Failure to meet the deadlines for submitting invoices issued offline to KSeF, as well as failure to issue a structured invoice despite such an obligation, will be subject to financial penalties. They will come into force on January 1, 2027. These penalties may amount to up to 100% of the VAT amount shown on the invoice or up to 18.7% of the total gross amount due for exempt entities – if the invoice does not include tax amounts.

It is therefore worth developing and testing procedures for using KSeF offline to avoid penalties.

Despite initial integration challenges, KSeF has the potential to permanently improve business and tax processes. However, this requires uncompromising digital accuracy and rapid adaptation to new, strictly defined time and technical frameworks on the part of entrepreneurs.

We invite you to contact our experts. We offer assistance in implementing KSeF, training employees, and adapting systems. With our knowledge, experience, and individual approach tailored to the needs of your company, we will implement the changes efficiently, safely, and on time!