OO_RATE_FOREIGN_BUYER: P_12 = 'oo' is for domestic reverse charge only

StandardKSeF FA(3), Polish national e-invoicing systemSeverityWarning: the invoice is accepted but should be correctedSyntaxFA(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

[OO_RATE_FOREIGN_BUYER] P_12 = 'oo' is for domestic reverse charge only. Use 'np I' or 'np II' for foreign buyers (§10.3, Appendix D #18)

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 / business_logic

Typical causes

Using domestic reverse charge code for foreign entity
Should use 'np I' or 'np II' for EU/non-EU buyers

Check your invoice

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Same check via API:

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

Related rules

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FOREIGN_CURRENCY_TAX_PLN Foreign currency invoice with tax amounts should include PLN conversions in P_14_*W…
KURS_WALUTY_Z_PLACEMENT KursWalutyZ at Fa level is ONLY valid for advance invoices (RodzajFaktury = ZAL or…
NEGATIVE_QUANTITY_NOT_ALLOWED Negative quantities (P_8B) are only allowed in corrective invoices (RodzajFaktury =…
NIP_IN_WRONG_FIELD Polish NIP detected in NrVatUE field - must be in NIP field for purchaser KSeF access…
P12_ENUMERATION P_12 must be one of
SELF_BILLING_PODMIOT3_CONFLICT Self-billing (P_17 = '1')

Frequently asked questions

What does OO_RATE_FOREIGN_BUYER mean?

OO_RATE_FOREIGN_BUYER is a ksef fa(3) rule: P_12 = 'oo' is for domestic reverse charge only. Use 'np I' or 'np II' for foreign buyers (§10.3, Appendix D #18)

Will my invoice be rejected because of OO_RATE_FOREIGN_BUYER?

No. OO_RATE_FOREIGN_BUYER is a warning: the invoice is accepted but the recipient sees the notice. Fix it anyway, warnings often become errors in later rule versions.

Which formats does OO_RATE_FOREIGN_BUYER 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.