Last updated: 13.02.2026
KSeF in Poland (2026) – Key Facts
| Area | What You Need to Know |
| Legal Framework | KSeF (Krajowy System e-Faktur) becomes the mandatory platform for issuing and receiving structured invoices in Poland. |
| Start of Obligation | 1 February 2026 for large taxpayers; 1 April 2026 for all other VAT-registered entities; 1 January 2027 for the smallest micro-entities. |
| Who Is Covered | All VAT taxpayers in Poland, including SMEs, micro-entrepreneurs and sole traders, with limited transitional exemptions. |
| Invoice Format | Structured XML invoices compliant with the FA(3) schema replace PDF and paper invoices as the legally valid format. |
| Invoice Numbering | Each invoice receives a unique KSeF identification number assigned by the system. |
| Submission Method | Invoices are issued within internal systems but become legally effective only once successfully transmitted to KSeF. |
| Access & Authentication | Access via Trusted Profile, qualified electronic signature, qualified electronic seal, token or KSeF certificate (from 2026). |
| Attachments | Only structured data compliant with the schema is allowed — PDF attachments are not recognised as formal invoice components. |
| Tax Authority Access | The Polish tax authority (KAS) obtains real-time access to invoice data. |
| Penalties | Financial sanctions for non-compliance apply from 2027, following a transitional adaptation period lasting until the end of 2026. |
National e-Invoicing System (KSeF) in Poland – New regulations
From 2026, issuing and receiving invoices in Poland will no longer be possible outside the Krajowy System e-Faktur (KSeF) – a mandatory, centralised e-invoicing platform developed by the Ministry of Finance. This change affects all VAT-registered entities in Poland, including large taxpayers, SMEs, micro-entrepreneurs, and even sole proprietors, who will all be required to issue and receive invoices in the same way, via the KSeF platform.
To remain compliant and avoid tax risks, Polish and foreign companies must prepare in advance by adjusting their systems, authorisations, and invoicing process to align with structured invoicing requirements.
What Is National e-Invoicing System (KSeF) in Poland?
KSeF (Krajowy System e-Faktur) is a centralised national electronic invoicing system for the issuance, receipt, and storage of structured invoices in a uniform XML format, replacing traditional paper and PDF invoices. The new format is based on a structured template called the FA(3) invoice schema.
What Changes in Practice Under KSeF?
The introduction of KSeF significantly alters the way invoices function in Poland. Instead of being exchanged directly between contracting parties in paper or PDF form, invoices must now be issued and received exclusively through the central KSeF platform in structured XML format.
Every invoice is subject to system validation and receives a unique KSeF identification number, which confirms its formal acceptance within the system. The buyer no longer receives the invoice directly from the seller but retrieves it from the central platform.
Only data compliant with the official FA(3) schema is recognised, meaning that traditional PDF attachments cannot serve as formal invoice components. At the same time, the Polish tax authority (KAS) gains real-time access to invoice data, increasing transparency and digital oversight.
How to Start KSeF Implementation Process in Poland?
To legally issue e-invoices via KSeF, a business must go through the following preparatory stages:
1. Access the KSeF Platform
- KSeF account is automatically generated based on the company’s tax ID (NIP)
In the case of individuals, authentication in the KSeF system may be carried out using:
• a Trusted Signature, and from 1 April 2026 – via the National e-Identification Node (SSO),
• a qualified electronic signature,
• a token (available until the end of 2026),
• a KSeF certificate.
Entities other than natural persons may authenticate in the system using:
• a qualified electronic seal,
• a token (available until the end of 2026),
• a KSeF certificate.
2. Submit ZAW-FA Authorisation
- File the ZAW-FA form (for entities other than natural persons) to authorise people/entities to issue invoices
- Assign internal employees or external accounting service providers
3. Choose Your Tools
Businesses should choose a technical model aligned with the scale of their invoicing operations and internal infrastructure.
- Government-Provided Applications
The Ministry of Finance offers official tools, including the “e-mikrofirma” application and the KSeF Taxpayer Application. These solutions are typically sufficient for businesses issuing a limited number of invoices and do not require system integration. - System-to-System Integration (API Model)
Entities processing a higher volume of invoices usually require automated communication between their internal accounting or sales software and the KSeF platform. API-based integration ensures efficiency, reduces manual workload and minimises the risk of structural errors. - Third-Party Software Platforms
Certain providers offer licensed solutions enabling structured invoice transmission within defined usage limits. These platforms may be appropriate for businesses seeking partial automation without implementing full-scale ERP integration.
Tip: Choose a tool proportionate to your invoicing volume – avoid overpaying for full ERP systems if you only issue a few invoices per month.
Authentication Mechanisms within the KSeF Framework
Secure access to the KSeF system is based on designated authentication instruments that enable authorised users and internal systems to transmit structured invoice data.
Tokens function as system credentials assigned to a specific taxpayer environment, allowing internal accounting or sales software to communicate directly with KSeF without repeated manual authentication. Once properly configured, they enable automated submission of structured invoices from within the company’s own system.
In addition, KSeF certificates – introduced from February 2026 – provide an additional layer of authentication and may be used alongside tokens to enhance security and regulatory control over system access.
What Happens If You Don’t Comply with National System of E-Invoices in Poland?
From 2027, non compliance – such as issuing invoices outside the KSeF system – will result in financial penalties and VAT risks. Enforcement will be carried out by the Polish Tax Authority (KAS).
To avoid sanctions, ensure:
- All invoices are issued and received via the KSeF platform
- You can verify, archive, and access KSeF-issued documents
- You comply with technical and authorisation requirements
Legal Support for Businesses Adapting to KSeF in Poland
Whether you’re a multinational group or a sole trader, our law firm provides support with KSeF adoption:
- Legal analysis of e-invoicing requirements
- Drafting internal policies and ZAW-FA authorisations
- Coordinating IT integration with your invoicing system
- Staff training in structured invoicing workflows
- Ongoing monitoring of KSeF compliance and post-go-live audits
Contact us to ensure your transition to KSeF is secure, timely, and fully compliant with Polish tax law.
FAQ: KSeF Implementation in Poland
What is KSeF?
KSeF (Krajowy System e-Faktur) is Poland’s National e-Invoicing System — a centralised platform operated by the Ministry of Finance that enables businesses to issue, receive, and archive structured electronic invoices in real time.
What types of transactions are subject to mandatory e-invoicing under KSeF?
The obligation to issue invoices through the National e-Invoicing System (KSeF) applies to all VAT-taxable transactions in Poland. This includes domestic supply of goods and provision of services in the context of B2B (business-to-business), B2G (business-to-government), and B2C (business-to-consumer) transactions.
When will e-invoicing become mandatory in Poland?
The Polish Ministry of Finance plans to make e-invoicing mandatory for all commercial transactions starting 1 February 2026. From this date, businesses will be required to issue and receive structured invoices via the National e-Invoicing System (KSeF), regardless of the size or nature of the transaction.
Can I send PDFs or scanned attachments?
No – KSeF only supports structured data within the FA(3) schema.
What happens if I miss the deadline to implement KSeF?
From 2027, you may face penalties, rejected invoices, and blocked VAT deductions.
Does the KSeF requirement apply to other businesses outside the VAT system?
KSeF is intended to be a universal e-invoicing system. The obligation to issue invoices in KSeF will ultimately apply to all taxpayers (active and exempt) who are required to issue invoices under Polish regulations.
However, there is a list of exemptions from the obligation to issue invoices in this system, which result from the specific nature of a given transaction, the status of the seller or the status of the purchaser.
