E-Invoicing in Poland: A Complete Guide to KSeF Compliance

E-Invoicing in Poland: A Complete Guide to KSeF Compliance

On 17 June 2025 the Council of Ministers approved a draft law amending the VAT Act and other related regulations. The law confirms that the use of the Krajowy System e-Faktur (KSeF) also known as Poland’s National e-Invoicing System will become mandatory. For most businesses the new e-invoicing requirement will apply starting from Feb 2026. The reform is part of Poland’s plan to digitalize the tax system to prevent tax fraud and improve efficiency.

In this blog we will explain everything businesses need to know about e-invoicing in Poland.

What Is KSeF – The National e-Invoicing System in Poland?

The Krajowy System e-Faktur (KSeF) or National e-Invoicing System is Poland’s official platform that enables businesses to issue and receive structured electronic invoices. 

It is managed by the Ministry of Finance and allows taxpayers to create as well as transmit and store structured invoices in XML format.

KSeF Implementation Timeline in Poland

Legal and Technical Updates in the June 2025 Legislative Reform

The June 2025 legislative reform introduces several legal and technical simplifications to help businesses transition to KSeF compliance.

• Continued Use of Cash Registers
  Businesses can continue issuing invoices through cash registers until 31 December 2026. This provides additional time for KSeF integration.
• KSeF Number Not Required in Payments
  Until the end of 2026, businesses are not required to include the KSeF invoice number in payment references. This also applies to split payments (MPP).
• Exemption for Small Businesses
  Businesses with total monthly sales below PLN 10,000 are exempt from mandatory KSeF usage until 1 January 2027.
• Optional Use for Specific Invoices
  B2C invoices and VAT RR invoices for purchases from flat-rate farmers are excluded from the mandate.
  Voluntary use of KSeF for VAT RR invoices is allowed from 1 April 2026.
• Structured Attachments Supported
  From 1 January 2026, businesses can send invoices with structured attachments (such as utility bills) through KSeF after submitting a request via the e-Tax Office.
• System Testing and Certificate Preloading
  The KSeF 2.0 test environment will open on 1 November 2025.
  Taxpayers will also be able to preload issuer certificates starting from November 2025 to prepare in advance.
• Faster VAT Refunds
  The standard VAT refund period will be reduced from 60 days to 40 days.

You can read the full official release from here.

The e-Invoicing Process in Poland

The e-invoicing process in Poland is managed through the KSeF, which ensures the structured and standardized exchange of invoice data between businesses and the tax authority.

• The seller will prepare an electronic invoice in the required XML format.
• The structured invoice will be submitted to KSeF through an API or another compatible connection.
• KSeF will carry out a technical and formal validation of the invoice to make sure it meets the required structure and content requirements.
• Once the invoice passes validation, KSeF assigns a unique KSeF identification number and records the official issue date of the invoice as the date of acceptance into the system.
• KSeF will then generate a confirmation of receipt (UPO), which will act as legal proof that the invoice has been issued.
• The approved invoice will be available to the recipient through their access to KSeF. The recipient can retrieve the invoice directly from the system.
• Both the seller and the buyer will be able to access the invoice using their own KSeF-integrated systems or user interfaces.

Scope of KSeF in Poland

Entities Required to Use KSeF

• VAT-registered businesses established in Poland

Entities Exempt from KSeF

• Businesses not established in Poland and without a fixed establishment in the country
• Foreign businesses with a fixed establishment in Poland, provided that establishment is not involved in the invoiced transaction
• B2C transactions, where reporting through KSeF is optional rather than mandatory
• Invoices valued below PLN 450, provided the total monthly amount does not exceed PLN 10,000; these are temporarily exempt during the transition period

Technical Requirements for E-Invoicing in Poland

• An electronic invoice must be prepared in the XML format based on the FA logical structure that is defined by the Ministry of Finance of Poland.
• Only structured XML files will be accepted on the KSeF platform. Any non-structured file such as a PDF or an image will not be allowed.
• The invoice must include the Polish NIP which is the tax identification number of the seller.
• For a B2B transaction, the NIP of the buyer will also be required.
• If the buyer is not registered for VAT or is a consumer, then the seller must include a field called BrakID which will show that the buyer does not have a tax identification number.
• If the KSeF platform is not available and the invoice is issued during this time, then specific rules will apply.
• In the case of offline mode, the invoice must be submitted to KSeF no later than the next working day.
• In the case of emergency mode, the invoice must be submitted within seven working days after the system becomes available again.
• Every structured invoice that is submitted to KSeF will be stored automatically for a period of ten years on the government system.
• Because of this built-in storage, the business will not be required to keep a separate archive of these invoices in its local system.

How to Prepare for KSeF as a Business

Businesses need to prepare in advance to comply with the KSeF mandate and manage both technical and operational requirements:

• Use the Correct FA XML Format

  Invoices must be in XML format based on the FA structure. A new version called FA(3) will include fields such as extended product names, employee details, and attachments. Businesses should check if their software supports this version.

• Choose KSeF-Compatible Software

  You can use your own ERP or accounting system connected to the KSeF API. Businesses that handle a high volume of invoices or require automation can choose dedicated e-invoicing solutions. For example, Flick’s e-invoicing software is fully integrated with KSeF and allows businesses to create, send, and track structured invoices with full compliance.

• Prepare for Offline and Emergency Use

  When the KSeF system is unavailable, invoices can be created in offline or emergency mode. These must be sent to KSeF within one working day in offline mode or within seven working days in emergency mode. Teams should be trained to follow the correct process in these cases.

• Train Accounting and IT Teams

  Businesses need to train staff involved in invoicing to use KSeF tools effectively, including how to send invoices and make corrections, by providing them with proper training resources.

• Test Your System with KSeF

  Before the deadline, businesses should test their setup using the KSeF demo or test environment. This helps identify issues early and confirms that the software and staff are ready for live operations.

  How Flick Network Can Help Your Business with E-Invoicing in Poland

Flick Network provides a full e-invoicing solution to help your business stay compliant with Poland’s KSeF system:

• KSeF API Integration

  Flick’s e-invoicing software is fully integrated with the official KSeF API, allowing you to send, receive, and manage structured invoices without needing a separate technical setup.

• FA(3) Structure Support

  The system is continuously updated to support the latest FA XML structure, including FA(3), so your business always meets technical and legal standards.

• User Access Control

  Assign roles and manage user access securely across teams and departments.

• Offline and Emergency Handling

  Flick enables invoice creation when KSeF is unavailable, and resubmits automatically within the required timeframe.

• Built-In Invoice Validation

  Flick performs real-time validation of invoice data before submission to KSeF. This helps reduce errors and avoids invoice rejection from the system.

• Multi-Entity Support

  If your business operates under multiple VAT numbers or has several branches, Flick can handle all of them under one platform with clear separation and control.

• Local Compliance Updates

  Our team tracks legal changes and keeps the system aligned with the latest KSeF requirements.

Conclusion

• KSeF will be mandatory for most of the businesses in Poland from February 2026. To get ready for this, we suggest using a KSeF-compatible e-invoicing software like flick e-invocing. It will help with automation and make it easier to send and receive a large number of invoices. If you have any questions or need help, you can contact us and we will be happy to assist.