On 27 August 2025, the President of Poland signed an amendment to the VAT Act, updating the deadlines related to the implementation of the National e-Invoicing System (KSeF).
What is KSeF?
KSeF is an IT platform for issuing, accessing, receiving, and storing structured invoices. Its purpose is to centralize the invoicing process in real time. The system also enables role and permission management, improving data security and ensuring that invoices are issued only by authorized persons.
The mandatory use of KSeF will apply to most VAT taxpayers, both active and exempt.
There are certain exceptions. The obligation will not apply to entities that do not have a registered office in Poland or that supply goods and services to individuals not engaged in business activity.
Furthermore, VAT RR invoices documenting the purchase of agricultural products from flat-rate farmers will not fall under the mandatory scheme. Issuing these documents in KSeF will be possible from 1 April 2026 on a voluntary basis. At the same time, from 1 February 2026, the preferential 40-day VAT refund period for entities using VAT RR invoices will be abolished.
KSeF Implementation Timeline
KSeF will be rolled out in two main stages, with an additional deferral for micro-enterprises:
- Starting 1 February 2026 – Large taxpayers (sales in 2024 exceeding 200 million PLN including VAT);
- Beginning 1 April 2026 – All other businesses, except micro-enterprises;
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Effective 1 January 2027 – Micro-enterprises and businesses with limited digital access (transactions up to 450 PLN per invoice and 10,000 PLN monthly).
Transitional Arrangements
Under the VAT Act amendment of 5 August 2025, companies with 2024 sales including VAT not exceeding 200 million PLN may, between 1 February and 31 March 2026, issue invoices electronically or in paper form.
Companies with monthly sales including VAT not exceeding 10,000 PLN may, between 1 April and 31 December 2026, also issue invoices electronically or in paper form.
Until the end of 2026:
- invoices from cash registers can still be issued;
- no penalties will apply for invoicing errors via KseF;
- there is no obligation to include the KSeF number in invoice payments (including under the split payment mechanism).
Errors or delays in submitting invoices during the first year of mandatory use will not be sanctioned.
Testing Phase and Pilot Environment
From 30 September 2025, the KSeF 2.0 API will be open for testing by integrators and large companies.
From November 2025, the Ministry of Finance plans to release a test version of the KSeF Taxpayer Application 2.0, allowing all businesses to explore the system's functionalities. Invoices issued in the test environment will have no legal effect, but they offer a unique opportunity to get familiar with KSeF.
The final version of KSeF, enabling invoices to be issued in real business transactions, will be available from 1 February 2026. From that date, taxpayers covered by the schedule will be required to issue invoices through KSeF.
Certificates
A KSeF certificate will be one of the methods of authentication in the system. From 1 November 2025, companies will be able to apply for invoice issuer certificates.
The certificate will be required to:
- authenticate invoices transmitted outside the KSeF system;
- confirm the identity of the issuer;
- enable secure login to KSeF and verification of user permissions.
Certificates will be issued for two years and can be renewed for another two years.
Applications may be submitted by:
- natural persons listed in the ZAW-FA notification;
- natural persons with ownership rights;
- legal entities with ownership rights, using a qualified electronic seal (in the case of companies – an authorized representative).
To log into KSeF, one of the following will be required: a qualified electronic signature, a qualified electronic seal, the Trusted Profile (Profil Zaufany), or a KSeF certificate.
Online and Offline Modes, Maintenance and Failures
KSeF allows invoicing in two modes:
Online mode – invoices are issued and transmitted in real time to KSeF;
Offline mode – invoices are initially created outside KSeF and subsequently uploaded to the system, particularly during maintenance periods, system failures, or connectivity issues.
Submission Deadlines
Deadlines for submitting invoices depend on the reason:
● System failure – invoices must be submitted within 7 business days after the failure ends;
● Maintenance work – invoices must be submitted within 1 business day after availability is restored;
● Total outage (e.g. war or natural disaster) – invoices may be issued in paper form;
● If the issue is on the taxpayer's side (e.g. internet outage or IT failure), invoices may be issued outside KSeF but must comply with the FA(3) schema and be submitted no later than the next business day.
KSeF Mobile App
Businesses will also be able to manage invoices via the free KSeF Mobile App (version 2.0). The app will be regularly updated and available in the Google Play Store and the Apple App Store. It will enable management of vendor profiles, customer databases, and banking information.
Summary
The mandatory use of KSeF will be a significant challenge for taxpayers. Updates to the FA(3) invoice schema and KSeF 2.0 API documentation are expected in the coming months.
Recommended Preparation Steps
Businesses should verify now whether their accounting and ERP systems can handle the updated FA(3) structure and are compatible with KSeF 2.0. This is the right time to train your teams and explore the pilot environment.
Even before the go-live date, you can obtain the necessary certificates and adapt your IT infrastructure – ensuring compliance with confidence and security.
Critical Timing Considerations
Since KSeF will become mandatory within a few months, we strongly recommend early preparation. KSeF implementation coincides with peak tax season, when finance and tax teams are already occupied with tax returns and financial reporting (February 1 and April 1, 2026).
Important Notice
This material does not constitute tax advice and reflects the legal status as of the date of preparation.
If you have any questions, please do not hesitate to contact us.
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