KSeF & Polish E-Invoicing
Poland's National e-Invoice System becomes mandatory in 2026. Everything you need to know about KSeF requirements, the FA(3) format, deadlines, and integration with PEPPOL.
Last updated: December 2025
What is KSeF?
KSeF (Krajowy System e-Faktur) is Poland's mandatory electronic invoicing system managed by the Ministry of Finance. All B2B invoices will need to be issued through KSeF, which provides:
- Centralized storage - All invoices stored securely by the government for 10 years
- Real-time validation - Invoices validated upon submission against the FA(3) schema
- Unique invoice numbers - Each invoice receives a KSeF reference number (numer KSeF)
- Faster VAT refunds - Potential for accelerated VAT processing for compliant businesses
- Reduced fraud - Central verification eliminates fake invoices
- No separate archiving required - Businesses don't need to maintain separate invoice archives for KSeF-issued invoices
- Standardized format - All invoices use the same FA(3) XML structure
KSeF Mandatory Deadlines (Confirmed)
February 1, 2026: Large taxpayers (annual revenue over PLN 200 million)
April 1, 2026: All other VAT-registered businesses
January 1, 2027: Micro-entrepreneurs (ryczałt, karta podatkowa)
The KSeF law was signed by President Andrzej Duda on August 27, 2025. A grace period applies until the end of 2026 with no penalties for technical errors.
KSeF (Krajowy System e-Faktur)
Poland's National e-Invoice System. A centralized platform for issuing, validating, and storing all B2B electronic invoices in Poland.
FA(3) Format
The latest XML schema for Polish e-invoices (replacing FA(2) from Feb 2026). Contains invoice data including P_1 (date), P_2 (number), seller/buyer NIP, and line items.
NIP Identifier
Numer Identyfikacji Podatkowej - the 10-digit Polish tax ID. Format: XXX-XXX-XX-XX. Used in KSeF and PEPPOL Directory lookups.
Who Needs to Comply with KSeF?
KSeF applies to most businesses operating in Poland, with specific rules based on business size and transaction type:
Must Use KSeF
- All VAT-registered businesses in Poland - Including sole traders, partnerships, and corporations
- Foreign companies with Polish VAT registration - If you have a fixed establishment in Poland
- B2B transactions - All invoices between VAT-registered businesses
Exemptions from KSeF
- B2C transactions - Sales to private individuals (consumers) are excluded from mandatory e-invoicing
- Digitally excluded micro-entrepreneurs - Businesses with monthly turnover below PLN 10,000 using simplified taxation (from January 2027)
- Certain cross-border transactions - Specific rules apply for invoices to foreign buyers without Polish NIP
Grace Period
The Ministry of Finance has introduced a grace period until the end of 2026 - no fines will be imposed for technical errors during this transition period. This gives businesses time to adapt their systems without penalty.
FA(3) Invoice Format
From February 2026, KSeF uses the FA(3) XML schema (replacing FA(2)). Key fields include:
| Field | Description | Example |
|---|---|---|
| P_1 | Invoice issue date | 2026-02-01 |
| P_2 | Invoice number | FV/2026/001234 |
| Podmiot1/NIP | Seller NIP (tax ID) | 5261234567 |
| Podmiot2/NIP | Buyer NIP (tax ID) | 7891234560 |
| P_13_1 | Net amount (23% VAT) | 1000.00 |
| P_14_1 | VAT amount (23%) | 230.00 |
| P_15 | Total gross amount | 1230.00 |
| P_3A | Sale/service completion date | 2026-01-31 |
| KodWaluty | Currency code (ISO 4217) | PLN |
| Podmiot1/Nazwa | Seller company name | ABC Sp. z o.o. |
| FaWiersz/P_7 | Line item description | Consulting services |
| FaWiersz/P_8A | Unit of measure | szt. (pcs) |
| FaWiersz/P_9A | Quantity | 10 |
KSeF vs PEPPOL
Understanding the difference between Poland's national system and the European network:
| Aspect | KSeF (Poland) | PEPPOL (Europe) |
|---|---|---|
| Scope | Polish domestic invoices | Cross-border European invoices |
| Format | FA(3) XML schema (from Feb 2026) | UBL 2.1 / PEPPOL BIS 3.0 |
| Identifier | NIP (10 digits) | Various (VAT, GLN, etc.) |
| Transmission | Central government platform | Decentralized access point network |
| Mandatory | Yes (Feb-Apr 2026 for B2B) | Varies by country (B2G often required) |
Poland is working on integrating KSeF with PEPPOL to enable seamless cross-border e-invoicing while maintaining domestic KSeF compliance.
How to Validate KSeF Invoices
Our free validator supports KSeF FA(3) format validation:
- Go to the PEPPOL Validator
- Upload your FA(3) XML file or paste the XML content
- The validator auto-detects KSeF format
- Review validation results with human-readable error explanations
- Fix any issues before submitting to KSeF
Common validation checks include NIP format, required fields, VAT calculations, and schema compliance.
Finding Polish Companies in PEPPOL
Search for Polish businesses registered on the PEPPOL network:
- Go to the PEPPOL Directory
- Enter the company's NIP (10-digit Polish tax ID)
- View registration details, document types supported, and access point
- Verify the company can receive PEPPOL e-invoices
Note: Not all Polish companies are on PEPPOL. KSeF is the primary system for domestic B2B invoicing in Poland.
KSeF Technical Requirements
Key technical milestones and requirements for KSeF integration:
| Milestone | Date | Details |
|---|---|---|
| API Documentation | June 30, 2025 | Full KSeF 2.0 API specs published |
| Test Environment | October 15, 2025 | KSeF 2.0 API pre-production environment published |
| Certificates Available | November 1, 2025 | KSeF authentication certificates issued |
| Demo Application | November 15, 2025 | KSeF 2.0 Taxpayer Application (pre-production) released |
| Large Companies Go-Live | February 1, 2026 | Mandatory for PLN 200M+ revenue |
| All Companies Go-Live | April 1, 2026 | Mandatory for all VAT taxpayers |
| Token Deprecation | January 1, 2027 | All users must use certificate authentication |
For Access Points: Integration requires FA(3) schema support, KSeF API connectivity, certificate-based authentication, and compliance with Polish e-invoicing regulations. Contact the Ministry of Finance for access point registration.