Compliance · 🇵🇱 Poland Phased rollout

Poland — KSeF mandatory B2B clearance

KSeF mandatory clearance · large taxpayers Feb 2026 · all April 2026 — regulator: Ministerstwo Finansów (Ministry of Finance). Facts last refreshed: 2026-05-05.

Coverage model

Flowie operates a registered Peppol Access Point in this jurisdiction directly where we hold national accreditation, or via a vetted local partner registered with the in-country regulator where on-the-ground presence is required (KSeF, SDI intermediario, ZATCA service-provider, etc.). Either way, you call the same POST /v1/documents/send.

TL;DR

KSeF (Krajowy System e-Faktur) is Poland's central clearance platform — every domestic invoice is submitted, validated, and assigned a KSeF number before being delivered to the buyer.
Mandatory from 1 February 2026 for taxpayers with sales > PLN 200M; 1 April 2026 for everyone else.
Format: FA(2) — Polish XML schema, mandatory; not interchangeable with Peppol BIS for domestic.
Cross-border invoices ride Peppol BIS as usual; only domestic KSeF.

Deadlines

Date	Who	What
2022-01-01	Voluntary KSeF	Available for early adopters.
2026-02-01	Large taxpayers (sales > PLN 200M)	KSeF mandatory.
2026-04-01	All other VAT taxpayers	KSeF mandatory.
2027-01-01	Cash register integration	POS systems must connect to KSeF for B2C documents.

Background

Poland operates the most aggressive CTC regime in the EU: clearance, not just reporting. An invoice does not legally exist until KSeF accepts it and returns a KSeF number. The seller can then deliver the invoice to the buyer (in any format), with the KSeF number as proof of validity.

Flowie's domestic Polish flow: POST /v1/documents/send → Flowie translates JSON to FA(2) → submits to KSeF → receives KSeF number and visualisation URL → returns those to the caller, then optionally delivers to the buyer (PDF or Peppol).

Format profile

FA(2) XML schema, defined by the Polish Ministry of Finance. No alternative for domestic.
Peppol BIS 3.0 for cross-border.
Polish NIP: 10 digits, prefixed with PL for VAT.

Required fields

seller.taxId.nipstring (10 digits)required

Polish NIP.
buyer.taxId.nipstring (10 digits)required for B2B

Buyer NIP.
ksef.invoiceTypecodeauto-derived

FA(2) document type code; derived from type when omitted.

Public sector (B2G)

Hub	Peppol identifier scheme	Lookup
KSeF (covers public + private)	`PL-NIP-<nip>`	https://www.podatki.gov.pl/ksef

KSeF is the universal Polish hub — public-sector recipients use it too. There's no separate B2G platform.

B2B reporting / clearance

KSeF — Clearance: invoice validated and assigned KSeF number before legal delivery.

Lifecycle status	Reported as
`issued`	Submitted; KSeF number returned.
`rejected`	Schema or business-rule failure; original FA(2) returned.
`cancelled`	Cancellation message; original KSeF number referenced.

Opt-out: settings.autoCompliance.PL = false (only for cross-border-only sellers)

Error codes

Code	Meaning	Fix
`KSEF-21100`	Schema validation failure on FA(2).	Inspect `error.details` for the offending element.
`KSEF-21102`	NIP not registered with KSeF.	Either party not yet onboarded; verify with the buyer.
`KSEF-22001`	Authentication token expired.	Flowie auto-refreshes; manual integrations must re-issue the JWT.

Testing in sandbox

What you want to test	How
KSeF happy path	Seller NIP `1111111111`, buyer NIP `2222222222`; sandbox returns synthetic KSeF number.
Force KSeF rejection	`simulateCompliance: "reject_KSEF_21100"`.

FAQ

Can I send PDF to the buyer if KSeF accepted the FA(2)?

Yes — once KSeF returns a number, the invoice exists. You may also deliver a human-readable PDF (with the KSeF number on it) to the buyer's mailbox, or send via Peppol if they prefer.

Are foreign sellers obligated?

Only if registered for Polish VAT. A foreign EU seller invoicing into Poland uses standard EU rules; KSeF is not required.

References

Primary sources (government / regulator / standards body):

EU Commission · eInvoicing in Poland — Pan-EU reference factsheet.
OpenPeppol · Poland profile — Authoritative Peppol facts.
KSeF · Krajowy System e-Faktur (MF) — National e-invoicing platform — Ministry of Finance.
Podatki.gov.pl · KSeF info portal — Taxpayer guidance and FAQ portal.
PEF · Platforma Elektronicznego Fakturowania — B2G Peppol-based platform.

Industry analyses (vendor trackers — useful for cross-referencing):

vatcalc · Poland KSeF 2026 timeline — Industry tracker — Feb/Apr 2026 phased rollout.