Official rule text
[CURRENCY_RATE_MISMATCH] KursWaluty does not match the NBP Table A mid-rate for the reference date (Art. 31a ustawy o VAT — the business day before the tax obligation arises, or before the issue date when the invoice precedes it)
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
Typical causes
- Manually entered exchange rate differs from the official NBP rate
- Rounding error in exchange rate
- Wrong date used for the exchange rate lookup — the issue date rather than the delivery or settlement-period date
- Taxpayer lawfully elected a different basis that FA(3) does not record: ECB rates (Art. 31a ust. 1) or income-tax conversion rules (Art. 31a ust. 2a)
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.
Same check via API:
curl -F file=@invoice.xml https://einvoicechecker.com/v1/validateRelated rules
CURRENCY_RATE_UNVERIFIABLEKursWaluty cannot be verified — NBP rate unavailable or outside the valid date window (ArtFOREIGN_CURRENCY_TAX_PLNForeign currency invoice with tax amounts should include PLN conversions in P_14_*W…KURS_WALUTY_Z_PLACEMENTKursWalutyZ at Fa level is ONLY valid for advance invoices (RodzajFaktury = ZAL or…NEGATIVE_QUANTITY_NOT_ALLOWEDNegative quantities (P_8B) are only allowed in corrective invoices (RodzajFaktury =…NIP_IN_WRONG_FIELDPolish NIP detected in NrVatUE field - must be in NIP field for purchaser KSeF access…OO_RATE_FOREIGN_BUYERP_12 = 'oo' is for domestic reverse charge onlyP12_ENUMERATIONP_12 must be one ofSELF_BILLING_PODMIOT3_CONFLICTSelf-billing (P_17 = '1')
Frequently asked questions
What does CURRENCY_RATE_MISMATCH mean?
CURRENCY_RATE_MISMATCH is a ksef fa(3) rule: KursWaluty does not match the NBP Table A mid-rate for the reference date (Art. 31a ustawy o VAT — the business day before the tax obligation arises, or before the issue date when the invoice precedes it)
Will my invoice be rejected because of CURRENCY_RATE_MISMATCH?
No. CURRENCY_RATE_MISMATCH 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 CURRENCY_RATE_MISMATCH 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.