Last updated: 01.01.2026 
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, companies in Poland 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.
Key regulatory changes under KSeF:
- As a rule, all invoices issued and received must pass through the KSeF platform in structured form.
- Buyers must download electronic invoices directly from KSeF
- Each invoice receives a system-assigned KSeF number (KSeF id)
- Only structured invoice attachments (not PDFs) are permitted in specific cases
- The tax authority gains real-time access to transaction data
The National e-Invoicing System will be mandatory and legally binding – invoices not submitted via KSeF will not meet statutory invoicing requirements, exposing businesses to compliance risks.
Mandatory E‑Invoicing in Poland: Ksef Implementation Timeline
| Implementation Date | Taxpayers Concerned | Notes |
| 1 February 2026 | Large taxpayers (with gross turnover exceeding PLN 200 million in the preceding year) | Start of mandatory use |
| 1 April 2026 | All other taxpayer | Includes sole traders and micro businesses |
| 1 January 2027 | Micro-enterprises / smallest businesses (monthly sales not exceeding PLN 10,000) |
Final phase of implementation |
| Until 31 Dec 2026 | All taxpayers | Grace period – no penalties yet |
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
- Free tools – The Ministry of Finance provides access to basic invoicing solutions, such as the “e-mikrofirma” application and the KSeF Taxpayer Application. These tools are generally sufficient for small-scale businesses with limited invoicing needs.
- IT integrations – For entities issuing a larger volume of invoices, automation becomes essential. This typically involves integrating existing sales or accounting systems with the KSeF platform via API.
- Commercial solutions – some software providers offer paid solutions that allow for a number of electronic invoices to be submitted annually, which may suit certain businesses.
Tip: Choose a tool proportionate to your invoicing volume – avoid overpaying for full ERP systems if you only issue a few invoices per month.
Tokens and Certificates – Essential for Secure KSeF Integration
- Tokens act as digital access keys, allowing invoicing systems to connect with KSeF seamlessly – no need for manual logins.
- KSeF certificates, available from February 2026, will be used in parallel with tokens and will constitute an additional form of authentication in KSeF.
- In practice, once configured, tokens enable invoices to be issued within a company’s internal system and automatically submitted to KSeF in structured form.
KSeF and Micro-Entrepreneurs: Key Considerations
Even freelancers, sole proprietors, and micro-entities are subject to the new e-invoicing regulations.
- Free tools are sufficient for issuing a handful of electronic invoices per month
- External support from accountants or software providers may be needed
- Business owners retain full responsibility for KSeF compliance – not the accounting office
Testing the E-Invoicing System
Failing to test your e-invoicing system KSeF connection is one of the most frequent (and costly) mistakes.
Benefits of early testing include:
- Familiarisation with the KSeF interface
- Full simulation of the electronic invoices flow (issuance – validation – receipt)
- Early detection of data errors
- Feedback on format issues or structural rejections
- Avoiding delays at the 2026 go-live date
KSeF offers a test environment (test version) – we recommend all businesses conduct full workflow tests before implementation.
Most Common Mistakes in KSeF Implementation
| Mistake | Risk | How to Avoid |
| Assuming the accountant will implement KSeF | Business remains legally responsible | Assign internal coordinator |
| Skipping test phase | Invoice rejections, cash flow issues | Use KSeF demo tools |
| Not filing ZAW-FA (for entities other than natural persons) | No access for employees or accountants | Submit authorisation early |
| Delaying tool selection | Incompatibility or system overload in 2026 | Match software to business scale |
| Using PDF attachments | System rejects non-structured data | Stick to FA(3) schema fields |
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?
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.
