Poland has just implemented one of Europe’s strictest electronic invoicing regimes. Since February 1, 2026, the national KSeF system (Krajowy System e-Faktur - National e-Invoice System) has been mandatory for large taxpayers, with the obligation extending to all Polish VAT-registered entities by April 1, 2026. For any French, German, or European company that invoices in Poland, operates through a permanent establishment, or holds a Polish VAT number, the question is no longer “when?” but “is my ERP connected to the right platform, with the right schema, in the right mode?”
KSeF doesn’t resemble the French Chorus Pro + accredited private platforms model, nor the Peppol network used in Germany and the Benelux. It’s a centralized clearance model: all invoices transit through the Polish Ministry of Finance platform, which assigns them an identifier and archives them. If your ERP can’t communicate directly with this platform in the expected format, it can no longer issue invoices in Poland, period.
This guide covers the rules in force since February 2026, the complete timeline, the FA(3) schema that replaces FA(2), and what your ERP must concretely be able to do, with an actionable checklist for a CTO or CFO discovering this complex topic.
KSeF: Poland’s centralized clearance model
Poland has made a different architectural choice from most of its neighbors. Where France has adopted a “Y” model (accredited private platforms + public PPF portal), Germany pushes Peppol as a decentralized infrastructure, and Italy operates SDI (Sistema di Interscambio) since 2019, Poland centralizes everything on a single platform managed by the Ministry of Finance (Ministerstwo Finansów).
How it works in practice. An issuer creates their invoice in their ERP, which serializes it in FA(3) XML format, sends it to the KSeF API via a certificate or authentication token, KSeF validates the schema, assigns a unique KSeF number, returns an acknowledgment (UPO, Urzędowe Poświadczenie Odbioru), and stores the invoice on the state side. The recipient then retrieves it in their own KSeF instance. There’s no PDF sent by email between parties, no Peppol network: everything goes through the state.
This model has a direct consequence on ERPs: they must integrate natively (or via a third-party connector) the KSeF API, manage authentication by qualified certificate, and store the returned KSeF number as accounting evidence. An ERP that merely generates XML for a third-party portal is not sufficient.
The 2026-2027 timeline: three phases, two thresholds
The KSeF 2.0 law was signed by Polish President Karol Nawrocki on August 27, 2025, then completed in December 2025 by four implementing regulations that locked in the operational framework (EY, Poland signs into law mandatory national e-invoicing system, Meridian Global Services, Four New Regulations finalised).
February 1, 2026: large taxpayers switch
Since this date, any company whose gross 2024 revenue exceeds 200 million Polish zloty (PLN), approximately 46 million euros, must mandatorily issue their B2B invoices via KSeF using the FA(3) schema. This concerns approximately 4,200 large taxpayers according to the Ministry of Finance (The Invoicing Hub, KSeF 2.0 launched on February 1, 2026).
This threshold is measured on 2024 revenue, not rolling data: a company that would exceed the threshold in 2026 would not enter this first wave, it would simply fall under the next phase.
April 1, 2026: all other registered entities
On this date, the obligation extends to all entities registered for Polish VAT, including SMEs, liberal professions and independent contractors (Sovos, KSeF timeline, EDICOM, Poland B2B mandatory e-invoicing).
January 1, 2027: micro-entrepreneurs
Final wave, taxpayers whose monthly sales are below 10,000 PLN (approximately 2,300 €) benefit from a reprieve until January 1, 2027 (Sovos, KSeF timeline).
This additional delay reflects political caution: forcing micro-entrepreneurs to integrate a government API would have generated massive rejection and requests for sectoral exemptions. The ministry therefore preferred to phase it.
Who is concerned if you are a foreign company
This is the point most poorly understood by CTOs outside Poland. A French, German or Spanish company can fall within the KSeF scope without having a subsidiary in Poland.
Case 1: permanent establishment in Poland. A subsidiary, branch, or operational office with personnel and infrastructure on site assimilates you to a Polish taxpayer. Your invoices issued from this establishment must go through KSeF from February 1 or April 1, 2026 depending on your size (Dudkowiak, E-Invoicing in Poland).
Case 2: Polish VAT number without permanent establishment. A foreign company registered for VAT in Poland, but without personnel or infrastructure on site (import-export, cross-border e-commerce, logistics), must use KSeF for invoices issued under this Polish VAT number from April 1, 2026. It doesn’t always benefit from the same exemptions as pure foreign buyers (Dudkowiak, E-Invoicing in Poland, EDICOM, Poland B2B mandatory e-invoicing).
Case 3: no establishment, no Polish VAT. A company that simply invoices a Polish client from abroad, without registering for VAT in Poland, is not required to use KSeF. However, its Polish client may require a compliant B2B invoice, which in practice forces issuing in FA(3) format to avoid friction.
For an ERP operated in France or Germany that manages Polish operations, the question to ask the vendor is simple: “Do you manage direct KSeF FA(3) issuance with Polish qualified certificate, for group entities with Polish VAT?” If the answer is no, you need either a third-party connector (Sovos, Comarch, EDICOM, Tradeshift), or an adaptation timeline that’s now too late to consider serenely.
What the FA(3) schema changes compared to FA(2)
The FA(2) schema has been entirely replaced by FA(3) on February 1, 2026. The KSeF 2.0 API documentation and final schema were published by the Ministry of Finance on June 30, 2025, leaving approximately seven months for vendors to adapt their connectors (VATupdate, Poland Releases Final KSeF 2.0 API Documentation and FA(3) Schema).
Three innovations deserve particular attention from an ERP perspective:
1. Attachments are finally managed
Since January 1, 2026, companies can attach complementary documents (technical specifications, delivery notes, product details) to structured invoices submitted to KSeF via the FA(3) schema. A taxpayer wishing to activate this functionality must declare their intention via the e-Tax portal (e-Urząd Skarbowy) before issuance (Fiscal Solutions, KSeF 2.0 launched, Sovos, KSeF 2.0 FAQs).
Concretely, an ERP must be able to generate the main invoice in FA(3), attach documents in base64 to the correct XML location, and store system-side the link between the KSeF invoice and its attachments for archiving. An ERP that has never had to handle this use case risks a gap in the audit trail.
2. “Offline24” mode absorbs outages
KSeF is a state platform, it can go down, and a company cannot stop invoicing because the ministry’s server has an incident. Offline24 mode allows the issuer to create a structured invoice offline, deliver it to the client, then submit it to KSeF no later than the next business day (Sovos, KSeF 2.0 FAQs).
For an ERP, this means implementing dual flow: nominal (immediate send to KSeF API with synchronous UPO return) and degraded (timestamped local storage, retry queue with automatic retry the next day). ERPs that don’t have a persistent queue will need to add one.
3. The format remains XML, not JSON
FA(3) is an XML schema, compatible with European UBL and CII models but with Polish-specific extensions. An ERP that already manages Factur-X (France) or XRechnung/ZUGFeRD (Germany) will have part of the work done on general grammar, but will need to add Polish-specific segments (VAT, JPK classification, KSeF-specific mandatory fields).
Penalties: one year of grace, then it hurts
The Polish legislator has provided for an acclimatization period to avoid administrative collapse in the first year.
From February 1 to December 31, 2026: no penalties for invoicing errors related to KSeF (Sovos, KSeF timeline). A company that issues a malformed, late or incorrectly metadata invoice will not be financially sanctioned, but must correct.
From January 1, 2027, the regime becomes punitive. Sanctions can reach 100% of the VAT amount indicated on the non-compliant invoice, or up to 18.7% of the total amount due on the invoice (Sovos, KSeF timeline). These are levels that turn an ERP bug into a direct financial incident.
The calculation to remember for financial management: an invoice of 100,000 PLN excluding tax with 23% VAT represents 23,000 PLN of VAT. In case of non-compliance after 2026, the maximum penalty on this single invoice reaches 23,000 PLN. On a portfolio of several thousand monthly invoices, the stake is sufficient to justify a five or six-figure ERP adaptation budget.
What your ERP must be able to do: technical checklist
A KSeF 2026-ready ERP must check the following seven boxes. If the vendor cannot answer affirmatively on each, it’s a red flag.
- Native FA(3) issuance. Generate complete FA(3) XML, with all Polish mandatory fields (JPK_V7 classification, PKWiU product codes, VAT by rate, mandatory mentions).
- KSeF portal authentication. Management of Polish qualified certificate, authentication token, and automatic renewal before expiration.
- UPO reception and storage. Consume KSeF response, capture unique KSeF number, store UPO (Urzędowe Poświadczenie Odbioru) in accounting document as issuance proof.
- Offline24 mode with queue. Persistent retry queue, double journaling (local and KSeF), alert if retransmission fails beyond 24h.
- Incoming invoice reception. Periodic interrogation of KSeF to retrieve invoices received under Polish VAT number, automatic integration into purchasing workflow.
- FA(3) attachments. Attach documents to XML schema in base64 if the company has notified its intention to the Polish administration.
- 10-year probative archiving. KSeF stores invoices, but the company remains required to keep its own copies with audit trail for 10 years, ERP must integrate this archive.
Among vendors currently cited as KSeF 2.0 compliant (non-exhaustive list, to be validated with the vendor at time of purchase): Comarch ERP (historical Polish vendor, most advanced on the subject), SAP S/4HANA with DRC add-on (Document and Reporting Compliance), Microsoft Dynamics 365 via partner connectors, Odoo via third-party modules (Mitxelena, Altabel), and specialized e-invoicing platforms (Sovos, EDICOM, Comarch e-Invoicing) that intercept upstream of the ERP.
How KSeF compares to other European models
For a European CTO managing multiple countries, here’s the quick reading of architectural differences:
| Country | Model | Platform | Private intermediary possible |
|---|---|---|---|
| Poland | Centralized clearance | KSeF (State) | No, KSeF mandatory |
| Italy | Centralized clearance | SDI (State) | No, SDI mandatory |
| France | ”Y” model (clearance + network) | PPF (State) + accredited platforms | Yes, via platforms |
| Germany | Decentralized Peppol | Peppol + Länder portals | Yes, Peppol Access Points |
| Spain | Real-time SII + future B2B | SII (VAT) + platforms | Yes, regional platforms |
Poland and Italy resemble each other in spirit (everything goes through the state, no intermediary), but KSeF goes further by requiring a stricter schema (FA(3)) and refusing PDF as probative document. A group operating in France, Germany, Italy and Poland will have to maintain four different connectors in its ERP, with four authentication logics and four data formats.
Checklist for a CTO or CFO discovering the topic
If you arrive on the subject in April 2026 with a Polish entity and an unprepared ERP, here’s the order of things to do:
- Map your entities. Which entity has Polish VAT? A permanent establishment? Do you invoice Polish clients from a French entity without Polish VAT?
- Measure 2024 revenue by Polish entity. Above 200M PLN, you’re already under obligation since February 1, and you’re potentially in default.
- Ask your ERP vendor for written confirmation. “Are you KSeF 2.0 FA(3) compliant in production mode, today, for Polish entities?” If yes, request the deployment kit. If no, request roadmap and timeline.
- If the vendor is not ready, evaluate a third-party connector. Comarch, Sovos, EDICOM, Tradeshift offer middleware solutions that intercept between ERP and KSeF. Typical budget: tens of thousands of euros in annual license plus integration.
- Provision a test in KSeF sandbox. The ministry maintains a public test environment, any production deployment must go through complete validation in sandbox (authentication, issuance, UPO reception, simulated outage management in Offline24).
- Train accounting. The KSeF number becomes a mandatory mention on accounting documents, bank reconciliations and customer matching change, the grace period until December 2026 is the opportunity to run in without financial risk.
Going further
KSeF is part of a broader European movement: France with Chorus Pro and accredited platforms, Italy with SDI, Spain with SII then the Crea y Crece law, and eventually the ViDA directive (VAT in the Digital Age) which aims for real-time VAT reporting across the EU by 2030.
For teams managing multi-country ERP who need to anticipate the regulatory wave, three complementary resources:
- The complete guide to mandatory electronic invoicing in Europe by 2027, which gives the timeline by country and accepted formats.
- The analysis of ERP for international trade and multi-country compliance, which covers the customs + tax + multi-jurisdiction compliance dimension.
- The ERP multi-site and multi-entity consolidation guide, useful for understanding subsidiary management in the context of divergent e-invoicing regulations.
For teams wanting to quickly validate their own preparation level, a 3-month POC focused on KSeF integration (FA(3) issuance, UPO reception, Offline24 mode) in ministry sandbox is the most rational step. Indicative budget: 20 to 40 K€ depending on ERP landscape complexity. Result: a documented go/no-go on your vendor’s ability to meet the deadline, before the grace period ends on December 31, 2026.
