KSeF mandatory from 1 February 2026 – President signs the law

On 27 August 2025, the President of Poland signed the Act of 5 August 2025 amending the VAT Act and the KSeF Act. This concluded the legislative process and confirmed that the National e-Invoice System (KSeF) will become mandatory from 1 February 2026.

The new regulations amend both the VAT Act of 2004 and the KSeF Act of 2023. The legislator’s aim, as indicated in the explanatory statement, is to give taxpayers sufficient time to adapt their accounting systems and to avoid unnecessary costs and disruptions to business activities.

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KSeF implementation schedule

The Act does not change the main date of entry into force of KSeF, which has been set for 1 February 2026. The obligation to use e-invoicing is expected to be introduced gradually in three stages:

• 1 February 2026 – the obligation will apply to large taxpayers, i.e. companies whose gross sales value for 2024 exceeded PLN 200 million,
• 1 April 2026 – the obligation will be extended to other entrepreneurs,
• 1 January 2027 – the implementation date has been postponed for the smallest companies whose monthly invoiced sales value does not exceed PLN 10,000 gross.

This schedule is intended to mitigate the effects of the reform and spread the obligations over time. In practice, however, this means that large companies will have to be ready for a full transition to the e-Invoice system by the beginning of 2026.

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Key changes introduced by the Act

As indicated in the explanatory statement, the solutions are intended to facilitate taxpayers’ preparation for mandatory e-invoicing, so that the implementation of the system into company accounting solutions takes place without excessive costs and the risk of disruption to business activities.

Obligation to issue e-invoices for all taxpayers

The Act stipulates that e-invoicing in KSeF will cover both active taxpayers and those exempt from VAT. At the same time, transitional provisions have been provided for, which allow the use of paper or electronic invoices in certain situations:

• from 1 February to 31 March 2026 – taxpayers entering the system earlier may continue to issue invoices outside KSeF if their sales in 2024 did not exceed PLN 200 million gross,
• from 1 April to 31 December 2026 – taxpayers may issue paper or electronic invoices if the total value of invoices in a given month does not exceed PLN 10,000 gross,
• from 1 February to 31 December 2026 – taxpayers obliged to use KSeF may issue invoices in the form of fiscal receipts from a cash register, recognised as invoices in accordance with Article 106e(5)(3) of the VAT Act.

Clarification of the ‘offline24’ mode

The amendment clarifies the rules for using the offline mode, i.e. issuing invoices outside KSeF in emergency situations. Clear rules have been introduced which specify:

• in which cases a taxpayer may use the offline mode,
• the deadline for sending such an invoice to KSeF after the technical problems have been resolved,
• how the date of issue and receipt of an offline invoice is treated.

Attachments to e-invoices as a new feature

Until now, KSeF did not provide for the possibility of sending attachments to invoices. The new regulations allow attachments to be added, provided that the intention to use them is notified in advance. The attachment will be treated as an integral part of the e-invoice, which will increase the usability of the system, especially in transactions requiring additional documentation.

Obtaining a KSeF certificate before the obligation comes into force

Taxpayers will be able to obtain an access certificate to KSeF in advance, starting from 1 November 2025. This will allow them to conduct technical tests and prepare their accounting systems in advance, before the obligation comes into force on 1 February 2026.

Changes to the deposit system

The Act also introduces episodic provisions (Article 145ka of the VAT Act) which adapt the regulations concerning the deposit system to the new legal reality.

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What does the President’s signature mean for entrepreneurs?

The President’s signing of the Act confirms that KSeF is becoming a reality. Companies should begin preparations in three key areas:

1. Technology – integration of accounting and ERP systems with KSeF.
2. Procedures – preparation of internal instructions, document circulation, archiving.
3. Cooperation with contractors – agreeing on the method of data exchange and handling exceptions.

This is not only a technical change, but also a reorganisation of many business processes – from accounting, through sales, to administration and controlling.

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Unanswered questions

Although the act concludes the legislative stage, many doubts remain in practice:

• Invoices outside KSeF – the regulations provide for situations in which it will be permissible to issue paper or PDF invoices. However, there is no uniform procedure for their verification and no certainty that they will always give the right to deduct VAT.
• Date of issue of the invoice – these regulations provide that the date of issue is the moment the invoice is sent to KSeF. This raises questions about periodic settlements and accounting practice.
• Employee invoices – the law does not specify the form in which invoices will be sent to employees making business purchases (e.g. fuel, accommodation).
• Foreign entities – the obligation to use KSeF will also apply to foreign companies with a permanent place of business in Poland. The ambiguity of the definition of this concept may lead to disputes over interpretation.
• Attachments to e-invoices – the regulations allow for their use, but do not specify how extensive the catalogue of accepted documents will be and how they will be treated by the tax authorities.

These issues could be resolved through tax explanations or general interpretations, which would provide taxpayers with greater certainty regarding the application of the new regulations. At this stage, however, the Ministry of Finance has indicated that it does not plan to issue such documents, focusing instead on information and training activities.

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How to prepare for KSeF?

Practice shows that the implementation of KSeF cannot be limited to installing a module in an accounting programme. Companies should take comprehensive measures:

• Process analysis – checking how invoices are currently issued and circulated within the organisation.
• Data mapping – adapting invoice fields to the FA(3) structure.
• Technical tests – launch integration with KSeF in a test environment, preferably before the end of 2025.
• Tax procedures – update VAT policies, define rules for offline invoicing and archiving.
• Training – prepare accounting and administrative teams to work with the new system.
• Cooperation with IT suppliers – adapting technical solutions to the needs of the company and its contractors.

It is crucial to start these activities in 2025 to avoid the risk of operational disruptions in 2026.

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Summary and recommendations

The signing of the act by the President is a turning point – from 1 February 2026, KSeF will become mandatory and will cover all VAT taxpayers. This means that companies must not only adapt their accounting systems, but also prepare themselves organisationally and procedurally. Time is running out – the implementation process should start now.

Mandatory e-invoicing is a significant challenge for businesses: it requires software updates, employee training, and the restructuring of certain business processes. At the same time, the reform offers an opportunity to:

• streamline document workflow and eliminate errors resulting from manual invoicing,
• increase the automation of accounting processes, which will save time and reduce costs,
• better control and transparency of settlements, which may ultimately reduce the risk of disputes with the tax authorities.

A well-planned implementation will help avoid problems in the first months of the system’s operation, such as delays in accounting, loss of liquidity or disputes with contractors.

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If you have any further questions or require additional information, please contact your business relationship person or use the enquiry form on the HLB Poland website.

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