Tax Alert: Introduction of KSeF confirmed

On 27 August 2025, the President of the Republic of Poland signed into law the Act amending the Act on Value-Added Tax and certain other acts (hereinafter: the KSeF Act). The new provisions (with certain exceptions) are expected to come into effect the day after they are announced.

The amendments brought about by the Act have been extensively explored in our Tax Alert, available in Polish (Tax Alert: Obowiązkowy Krajowy System e-Faktur coraz bliżej), when the act introducing the mandatory use of KSeF was still a bill. As a reminder, set out below are the key amendments introduced by the KSeF Act, in their adopted form. 

The Act establishes a requirement for all taxpayers (including both active and VAT-exempt taxpayers) to issue electronic invoices, introduced in two main stages, with a further deferral for the smallest businesses, namely:

• from 1 February 2026, the obligation will apply to the largest taxpayers (those with a 2024 sales value exceeding PLN 200 million, including tax);
• from 1 April 2026, the obligation will extend to other businesses, excluding the smallest enterprises (i.e. taxpayers whose monthly sales, including tax, do not exceed PLN 10,000). For these taxpayers, the requirement will take effect from 1 January 2027.

Furthermore, the Act introduces a permanent option to use the ‘offline24’ mode, allowing electronic invoices to be issued offline, outside the KSeF, and uploaded to the system immediately (at the latest, on the following working day). Importantly, the date of invoice issue will be the date visible in the content of the e-invoice, given by the taxpayer (field "P_1"). 

In addition, the new regulations allow invoices to be issued with attachments (for example in cases involving complex data structures relating to units of measurement, quantities of goods or unit prices). This solution, however, will be available on demand, upon filing a relevant request with the Head of the National Revenue Administration.

Additionally, the Act provides for:

• the possibility, from 1 April 2026, of issuing VAT RR invoices documenting in the system the purchase of agricultural products from lump-sum farmers;
• the postponement until the end of 2026 of the requirement to provide the KSeF number in payments for e-invoices (including those made under the split payment mechanism);
• the extension of the list of entities to which invoices may be sent outside the KSeF, to include natural persons not conducting business activity as well as entities without identification numbers;
• the postponement until the end of 2026 of penalties for errors related to invoicing via KSeF;
• the continuation until the end of 2026 of the option of issuing invoices via cash registers;
• clarification of the rules on consumer invoices, allowing them to be issued within KSeF;
• the simplification of the settlement of corrective invoices issued through KSeF;
• new obligations for purchasers of goods and services, i.e. a solution commonly referred to as purchaser self-identification (the purchaser of a structured invoice must provide their VAT number if registered for VAT purposes, or their tax identification number (NIP) if not registered (including exempt entities), where purchases are made for business purposes and such a number is available).

Although the new system will come into force on 1 February 2026 (for large taxpayers) and on 1 April 2026 (for other taxpayers), it must be remembered that the following stages of implementation of the mandatory KSeF are approaching:

• 30 September 2025 – open testing of the application programming interface (API) with KSeF 2.0 (the version to be used from 1 February 2026) will be available to all integrators and large companies;
• November 2025: 
  • release of a test version of the KSeF 2.0 Taxpayer Application. Invoices issued in the KSeF 2.0 test environment (API and Taxpayer Application) will not have legal effect,
  • release of certificates: entrepreneurs will be able to apply for invoice issuer certificates. The certificates will allow authentication in the system and will be required for issuing e-invoices in the event of a system failure or when using the ‘offline24’ mode once the KSeF becomes mandatory;
• 1 January 2026 – notification of the intention to issue invoices with attachments;
• 1 February 2026 – launch of the production version of the system, allowing invoices to be issued in actual business transactions.

The amending act introduces fundamental changes to invoicing, requiring taxpayers to transition from traditional to electronic invoicing. Compliance with KSeF will necessitate a wide range of adjustments, from invoicing processes themselves to internal procedures and external relationships with contractors. The first stage of KSeF implementation begins on 1 February 2026. Businesses should therefore commence preparations without delay, including analysing data, updating internal and external processes, and developing a clear implementation road map.

KPMG is ready to support you throughout the process: from providing practical guidance and addressing specific questions, to assisting with implementation and offering ongoing support once the system is deployed.

If you have any questions or require further assistance, please do not hesitate to contact us.