Electronic invoice in Poland
Comprehensive guide to mandatory B2B electronic invoicing in Poland – Legal framework, KSeF platform, obligations, and practical implementation
Overview
Poland operates KSeF (Krajowy System e-Faktur), a central government platform for issuing, transmitting, receiving and storing invoices. Mandatory use for domestic B2B transactions has been in force since February 2026 and was extended in April 2026 to all VAT-registered businesses.
The legal basis is the Act on the National e-Invoicing System together with the EU derogation (Council Implementing Decision 2022/1003). KSeF is not merely a transmission channel but a continuous transaction control system: every invoice is validated, assigned a unique KSeF number and timestamp, and becomes immediately available to the tax administration.
All VAT payers
from large groups to sole traders, with limited transitional relief
FA(3)
the binding XML schema defined by the Ministry of Finance
10 years
invoices are retained inside KSeF itself
Timeline
The rollout was staggered by company size. 2026 is structured as an adaptation year: the obligation applies, but the sanctions come later.
Already in force
April 2019
B2G receiving obligation via PEF
Public contracting authorities must be able to receive structured electronic invoices — through the PEF platform, based on Peppol BIS Billing 3.0.
1 February 2026
KSeF mandatory for large taxpayers
Businesses with turnover above PLN 200 million in the reference year must issue invoices through KSeF. The FA(3) schema becomes binding at the same time.
1 April 2026
KSeF mandatory for all remaining VAT payers
All businesses registered for VAT in Poland must issue and receive invoices through KSeF. Paper, PDF and other unstructured invoices are no longer permitted for domestic B2B.
Still ahead
31 December 2026
End of the adaptation period
Until the end of the year transitional arrangements apply: the offline mode stays open, token authentication remains usable, and breaches are not yet met with KSeF-specific fines.
1 January 2027
Micro-enterprises join and penalties begin
The final group — the smallest businesses with very low invoice volumes — is brought into scope. KSeF penalties take effect on the same date.
The adaptation period is not a postponement of the obligation. Anyone still invoicing outside KSeF today is already non-compliant — only the specific fines start later. Several reliefs also expire simultaneously at the turn of the year.
How KSeF works
The decisive difference from decentralised models such as Peppol: invoices are no longer exchanged directly between trading partners. The seller transmits the invoice to the central platform and the buyer retrieves it from there.
01
Creation in your own system
The invoice is created in your ERP or accounting system as before, but must conform to the FA(3) schema.
02
Transmission to KSeF
The invoice is sent to the platform and validated structurally. It only takes legal effect once accepted into the system.
03
KSeF number and timestamp
Every accepted invoice receives a unique identifier. It is the evidence that the invoice formally exists.
04
Retrieval by the recipient
The buyer no longer receives the invoice from the seller but collects it from KSeF. Delivery failure in the conventional sense ceases to exist.
05
Access for the tax administration
The Polish tax authority KAS has direct access to invoice data. Parts of the existing VAT reporting are replaced as a result.
A practical consequence: a PDF may still be produced and sent as a visual document, but it is not an invoice. Nor do PDF attachments count as part of the invoice — only data conforming to the schema is recognised.
Scope
Domestic B2B
Mandatory. All invoices between businesses registered for VAT in Poland travel through KSeF.
B2G
Mandatory. Submission through KSeF or through PEF; the two routes are linked.
B2C
Out of scope. Invoices to private individuals are not covered by the KSeF obligation. Voluntary issuance through KSeF is possible.
Cross-border
Invoices to foreign customers must be issued in KSeF but delivered to the trading partner by conventional means — for example as a visual document carrying the KSeF number.
For foreign businesses
What matters is whether a fixed establishment in Poland is involved in the supply. A VAT registration alone, without a fixed establishment, does not normally trigger the issuing obligation. Preparing on the receiving side is worthwhile regardless: Polish suppliers now issue exclusively through KSeF.
B2G and PEF
Poland had a dedicated infrastructure for public-sector invoicing well before KSeF: the PEF platform (Platforma Elektronicznego Fakturowania), built on Peppol. Since April 2019 public contracting authorities have had to accept structured invoices.
—Submission is possible through PEF (Peppol BIS Billing 3.0 under EN 16931) or through KSeF (FA(3) schema)
—The two routes are connected: invoices submitted via PEF also receive a KSeF number
—Public contracting authorities must accept structured invoices in the applicable format
—For foreign suppliers the Peppol route is usually the more practical one, as no Polish KSeF authentication is required
Poland therefore runs a dual-track approach: a central clearing system domestically, and a connection to the European Peppol network internationally.
Formats and standards
FA(3) – the KSeF schema
An XML structure defined by the Polish Ministry of Finance, binding for every invoice transmitted through KSeF. It replaced the earlier FA(2) schema and adds fields for data analysis.
Peppol BIS Billing 3.0
Used for the B2G route via PEF and for cross-border traffic. In Poland the specification also serves as the national CIUS, ensuring alignment with EN 16931.
For businesses trading in several countries this means the underlying data is the same; only the target syntax differs. Given clean data in the ERP, both can be generated from a single source.
Access and authorisations
A KSeF account is created automatically on the basis of the tax identification number NIP — no separate registration is needed. What does need to be settled is who may act on behalf of the business and with what they authenticate.
Authentication methods
—Qualified electronic seal — the usual route for legal entities
—Qualified electronic signature or Trusted Profile for natural persons
—KSeF certificate — available since February 2026 and intended for system integration
—Token — usable until the end of 2026, after which the certificate process replaces it
The ZAW-FA form
Legal entities use the ZAW-FA form to authorise people and organisations to issue and retrieve invoices on their behalf — employees, an accounting firm or a service provider. Without authorisations in place, nobody can act even where the technical connection is live. This step is routinely underestimated in implementation projects.
Offline mode and outages
Because an invoice only takes effect once accepted into KSeF, there has to be a rule for when the system is unavailable. The answer is issuance in offline mode with subsequent submission.
The invoice is issued outside the system and transmitted to KSeF once the connection is restored
It carries a QR code allowing the recipient to verify it before it is registered in the system
Extended offline use is permitted until 31 December 2026; tighter conditions apply thereafter
Offline mode is an emergency measure, not a operating model. Using it routinely simply defers the problem — the submission deadlines keep running.
Retention
One notable difference from every decentralised model: KSeF archives the invoices itself, for ten years from the end of the year of issue. No separate archiving of invoices issued through KSeF is required for VAT purposes.
Authenticity, integrity and legibility are assured by the system
For B2C invoices and documents outside KSeF, your own retention obligation remains
For your own audit and accounting purposes a local copy of the XML files is still advisable
Relying entirely on the state archive means handing over control of your own records. A mirrored store in your own DMS costs little and avoids dependencies when an audit comes.
Penalties
Throughout 2026 an adaptation period applies with no KSeF-specific fines. From 1 January 2027 sanctions take effect, enforced by the Polish tax administration KAS.
—Issuing invoices outside KSeF where the obligation applies
—Failure to submit within the prescribed period after an offline issuance
—Issuing in a format that does not conform to the applicable schema
The knock-on effect often weighs more heavily than the fine itself: a document without a KSeF number is not a proper invoice. That directly affects the customer's input VAT deduction — and therefore the business relationship.
How we help
As a certified Peppol Access Point and e-invoicing provider we cover both Polish routes — KSeF for domestic traffic, Peppol for B2G and cross-border:
Conversion of your invoice data into the FA(3) schema or Peppol BIS Billing 3.0
Transmission to KSeF and retrieval of incoming invoices
Authentication via qualified seal or KSeF certificate
Return of the KSeF number and status into your ERP system
Validation before submission — errors surface before transmission, not after
B2G submission via PEF and Peppol
Integration via API, SFTP and CSV
Ongoing adaptation to schema changes and new requirements
Frequently asked questions
Can I continue to use PDF invoices?
Not as an invoice for domestic B2B. Only the structured XML file in KSeF has legal effect. A PDF may still be produced and sent as a visual document — for foreign partners or internal filing — but it does not replace the KSeF invoice. PDF attachments are likewise not part of the invoice. For B2C invoices PDF remains acceptable.
What if my trading partner is not ready for KSeF?
For domestic B2B transactions it makes no difference: the invoice counts as issued and delivered once accepted into KSeF, whether or not the recipient retrieves it. The buyer's consent is not required — the obligation follows from the law. In practice it is still worth sending a visual document while your partner's processes are settling in.
Do small businesses have to comply as well?
Yes. Since April 2026 the obligation covers every VAT-registered business — including micro-enterprises and sole traders. Only the smallest group with very low invoice volumes has transitional relief running into early 2027. For businesses issuing few invoices the Ministry of Finance provides free tools, including the e-mikrofirma application, the KSeF Taxpayer Application and a mobile app.
Are foreign businesses affected?
The test is whether a fixed establishment in Poland is involved in the supply. If not, the issuing obligation does not normally apply — the specific facts should be reviewed with a tax adviser. Preparing on the receiving side is advisable in any case, since Polish suppliers now invoice exclusively through KSeF.
What happens if KSeF is unavailable?
The invoice may be issued in offline mode and handed to the recipient with a QR code. Once the system is reachable again it must be submitted within the prescribed period. Extended offline use is permitted until the end of 2026; tighter conditions apply thereafter.
Do I need to archive invoices separately myself?
Not for VAT purposes: KSeF retains invoices for ten years. For documents outside the system — B2C invoices, for instance — your own retention obligation continues. Independently of that, a local copy of the XML files is advisable for accounting and internal audit.
Summary
Poland is among the front-runners for mandatory B2B e-invoicing in the EU. KSeF has been in force since February 2026 and has applied to all VAT-registered businesses since April 2026. Paper and PDF invoices are no longer permitted in domestic trade.
The model is a central clearing system and therefore considerably more interventionist than the decentralised Peppol approaches used in Luxembourg or Slovakia: an invoice only comes into legal existence once accepted by the state platform, and the recipient retrieves it from there. At the same time Poland maintains alignment with the European standard through PEF and Peppol BIS Billing 3.0.
The grace period ends on 1 January 2027: penalties take effect, offline mode is restricted and token authentication expires. Anyone still working with interim arrangements should use the remaining months to build a clean system connection.
Resources
KSeF – the official Ministry of Finance portal
Central hub with the timeline, guidance, technical notices and login (in Polish)
Implementation stages of KSeF
Official overview of the deadlines and the steps required at each stage
KSeF 2.0 – questions and answers
Official FAQ organised by audience, from small businesses to IT integrators
Support for IT integrators
Technical documentation, interfaces and test environment
PEF – the public procurement e-invoicing platform
The B2G route, built on Peppol
European Commission – eInvoicing in Poland
Country factsheet covering the legal position, operating model and implementation status
OpenPeppol
Network, specifications and certified access points
