P6_P6A_MUTUAL_EXCLUSION: P_6 (common delivery date) and P

StandardKSeF FA(3), Polish national e-invoicing systemSeverityError: the invoice is rejectedSyntaxFA(3) XMLApplies toStructured invoices (FA(3) schema) submitted to the Polish KSeF. XSD codes come from the schema, semantic codes from the Ministry of Finance information sheet; KSeF rejects invoices that fail an error-level rule.

Official rule text

[P6_P6A_MUTUAL_EXCLUSION] P_6 (common delivery date) and P_6A (per-line delivery date) are mutually exclusive (§9.2, §10.2, Appendix D #8)

Why this error occurs

KSeF checks the FA(3) XML in two stages: XSD schema (structure, element order, data types, patterns such as NIP or dates) and semantic rules from the Ministry of Finance information sheet (consistency of amounts, annotations P_16 to P_23, roles of Podmiot2/Podmiot3, bank account formats, currency rates).

How to fix it

Fix the element named in the message. For XSD errors compare the element order and value pattern with the FA(3) schema; for semantic errors apply the cause and fix hints listed on this page. Re-validate before submitting to KSeF: a rejected invoice has no KSeF number and is not issued.

What the validator checks

Check levelsemantic / consistency

Typical causes

Both P_6 in Fa and P_6A in FaWiersz are present
Mixed delivery date specification

Check your invoice

Drop your XML or PDF on the validator and every failed rule is linked to its page here. Free, no account, the file is not stored.

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Same check via API:

curl -F file=@invoice.xml https://einvoicechecker.com/v1/validate

Related rules

DUPLICATE_LINE_NUMBERS Line numbers (NrWierszaFa) must be unique within the invoice (except in corrective…
GV_REQUIRES_PODMIOT3 When Podmiot2/GV = '1', at least one Podmiot3 must exist with Rola = '10' (§6.1,…
JST_REQUIRES_PODMIOT3 When Podmiot2/JST = '1', at least one Podmiot3 must exist with Rola = '8' (§6.1,…
KOR_NRKSEF_CONSISTENCY DaneFaKorygowanej
KURS_WALUTA_PAIR KursUmowny and WalutaUmowna must both be present or both absent (§13.1, Appendix D #11)
NST_LOGIC NoweSrodkiTransportu
PAYMENT_ZAPLACONO_DATE When Platnosc/Zaplacono = '1', DataZaplaty must be present (§12.1)
PMARZY_LOGIC PMarzy

Frequently asked questions

What does P6_P6A_MUTUAL_EXCLUSION mean?

P6_P6A_MUTUAL_EXCLUSION is a ksef fa(3) rule: P_6 (common delivery date) and P_6A (per-line delivery date) are mutually exclusive (§9.2, §10.2, Appendix D #8)

Will my invoice be rejected because of P6_P6A_MUTUAL_EXCLUSION?

Yes. P6_P6A_MUTUAL_EXCLUSION is flagged "fatal"; validators (KoSIT, Peppol access points, the German ZRE/OZG-RE portals, KSeF) reject the invoice until it is fixed.

Which formats does P6_P6A_MUTUAL_EXCLUSION apply to?

Structured invoices (FA(3) schema) submitted to the Polish KSeF. XSD codes come from the schema, semantic codes from the Ministry of Finance information sheet; KSeF rejects invoices that fail an error-level rule. Syntax: FA3.

Source: KSeF FA(3) schema 1-0E + semantic rules (@ksefuj/validator 0.4). Catalogue generated from the official rule sets on 2026-10-15.

P6_P6A_MUTUAL_EXCLUSION: P_6 (common delivery date) and P_6A (per-line delivery date) are mutually exclusive…