Poland has entered a new era of digital tax transformation. The National e‑Invoice System (KSeF) went live in February 2026, and the mandatory use of the National e-Invoice System is being introduced in phases during 2026. For many businesses this reshapes how invoices are issued, received, and reported. It is one of the most significant compliance shifts currently underway in the EU.
Why KSeF Matters
KSeF is a centralized government platform for structured invoices that replace PDF and paper invoices. In-scope invoices are submitted through the system, and once an invoice is sent and accepted by the Ministry of Finance, KSeF assigns a unique identification number, returned in the official acknowledgement (UPO), making it legally effective and immediately visible to tax authorities. From February 1, 2026, FA(3) is the mandatory structure for structured invoices issued in KSeF.
Key Deadlines
1. 1 Feb 2026: Mandatory for large taxpayers (2024 turnover incl VAT > PLN 200M); receiving invoices through KSeF also becomes mandatory from that date.
2. 1 Apr 2026: Mandatory for all other entrepreneurs (remaining VAT-registered businesses, including foreign VAT-registered companies without an FE) issuing in-scope invoices, subject to a temporary relief where the gross monthly value of the invoices covered, does not exceed PLN 10k
3. 1 Jan 2027: The temporary relief of PLN 10k- ends (monthly gross sales), so those taxpayers also fall fully into the mandatory regime from then on.
4. Grace Period (Enforcement Delay): it was indicated by the Polish Ministry of Finance a grace period is applicable from February 2026 to December 2026 during which the financial penalties would be mitigated if KSeF is not used correctly” during this period. Transitional allowances permit certain small businesses or transactions to temporarily use non-KSeF methods.
5. Full Enforcement: January 1, 2027. Full mandatory scope, with penalties beginning
What Changes in Practice
• Invoices must be issued and received through KSeF — no more PDFs.[1]
• System based validation and standardized invoice data increase visibility for the tax authorities, and change how businesses manage invoice controls and workflows.
• Offline24 mode allows invoice issuance during connectivity issues.
• Foreign companies without a Polish seat and fixed establishment are not required to use KSeF.
E‑Reporting Upgrades
To support the KSeF mandate, Poland is updating the JPK_VDEK schema to introduce new mandatory invoice reference fields. Going forward, VAT reporting data should include one of the following for each reported invoice:
- A KSeF identification number, or
- One of three reference codes, where a KSeF number is not available:
- OFF
- BFK
- DI
These fields are mandatory under the updated schema. If they are not present in the VAT return data, the JPK_VDEK submission will fail validation and the return will be rejected by the Polish tax authority. As there is no known grace period, data completeness is essential.
What Companies Need to Do Now
• Integrate ERP systems with KSeF APIs or deploy middleware.
• Map invoice data to FA(3) structured schema.
• Prepare AP/AR teams for new validation, issuance, and receipt workflows.
• Complete internal and integration testing in KSeF 2.0 environments as early as possible, and align production readiness with the live mandatory timeline.
KSeF represents one of Europe’s most advanced e‑invoicing mandates. Companies that adapt early will be better placed to manage automation, controls, and stronger readiness. At the same time, implementation should reflect the actual scope, phased rollout and new JPK reporting mechanics. For 2026, the Ministry of Finance has indicated that there should be no penalties for incorrect use of KSeF.
Check out our website for more insights: VATWorkx – For Tax Intelligence
[1] Note that B2C invoices remain outside the obligation and the law also provides specific exclusions for certain foreign taxpayer cases, special procedures such as OSS non-Union, IOSS, and SME, and some ticketing and other specific cases.
