How is a foreign-currency invoice handled in e-invoice?
Short answer
Distinguish the document currency from the tax currency. The XML must contain the correct DocumentCurrencyCode and, where VAT must be expressed in euros, the corresponding tax-currency data. VAT conversion follows the VAT Act, particularly § 26, together with the entity’s applicable accounting rules; it is not an arbitrary conversion.
Currency of the document
Specifies the currency in which the main invoice amounts are expressed.
Tax currency
It is used if VAT needs to be expressed in a different currency.
VAT conversion
The exchange rate rules belong to the tax assessment.
Same logic
ERP, XML and visualization must fit together.
Detailed explanation
Foreign currencies are a common source of errors, as PDF, ERP and XML formats may use different rounding rules or even a different currency. In a Peppol invoice, the currency is a machine-readable field linked to the amounts in the line items, tax totals and grand totals. If Slovak tax rules require VAT to be stated in euros, this must not be addressed by means of a free-form note, but by a correct entry in accordance with the supported fields and rules.
As set out in the law and technical rules
Section 26 of the VAT Act governs the conversion of foreign currencies into euros for VAT purposes. The content of the invoice is set out in Section 74. The electronic format is specified by EN 16931 and Peppol BIS Billing, in particular the fields for the document currency and the tax currency.
Practical examples
- The invoice is in CZK and VAT must be expressed in EUR. The XML must distinguish between the document currency and the tax currency.
- The ERP system converts VAT according to the approved exchange rate, and the XML file must use the same amounts as the accounting document.
- The PDF shows USD, but the XML shows EUR. This is a discrepancy that must be corrected before sending.
Common misconceptions
- “The exchange rate will be added by the validator.” No. The validator checks the rules; it does not make tax decisions.
- “It is sufficient to include the currency in the note text.” No. It must be in the structured fields.
- “A difference of a few cents doesn’t matter.” It may cause business rule errors and VAT discrepancies.
Conclusion
Keep the document currency, tax currency, exchange-rate basis, VAT calculation and rounding mutually consistent.
Legal and technical basis
- Act No. 222/2004 Coll. on VAT, Section 26
- Act No. 222/2004 Coll. on VAT, Section 74
- EN 16931
- Peppol BIS Billing 3.0, DocumentCurrencyCode and TaxCurrencyCode
Related questions
This is not legal advice. Sources: Act No. 222/2004 Coll. on VAT, Act No. 431/2002 Coll. on Accounting, Act No. 385/2025 Coll., official methodological and information materials from the Slovak Financial Administration on e-invoicing, EN 16931, Peppol BIS Billing 3.0 and OpenPeppol eDelivery documentation. Verified on 13 July 2026.
Official cases from the Slovak Financial Administration’s FAQs
The following questions and answers are taken from the current July FAQ from the Financial Administration and have been assigned to this topic. Grouping the cases prevents the creation of duplicate pages, whilst retaining the full answer and the exact wording of the question.
Example No. 64: How is VAT calculated from the tax base for e-invoices in a foreign currency (BIS Billing 3) converted to euros in accordance with Section 26 of the VAT Act, or from a tax base in a foreign currency with the VAT subsequently converted to euros, and what exchange rate should be used for this conversion?
Section 74 of the VAT Act, in accordance with Directive 2006/112/EC, stipulates that a mandatory element of an invoice, pursuant to point (i) of this provision, is the total amount of tax in euros payable, excluding the amount of tax applied under the special provisions of Section 66. If payment is required upon the supply of goods, the provision of services or the acquisition of goods within the country from another Member State in a foreign currency, such payment shall, pursuant to Section 26(1) of the VAT Act, be converted into euros for the purposes of determining the tax base using the reference exchange rate set and published by the European Central Bank or the National Bank of Slovakia on the day preceding the day on which the tax liability arises. A person liable to pay tax may use the exchange rate applicable under customs regulations on the date on which the tax liability arises to convert foreign currency into euros; the decision to use the exchange rate applicable under customs regulations must be notified in writing to the tax office prior to its first use and is binding for the entire calendar year. When correcting the tax base in accordance with Section 25, the exchange rate used at the time the tax liability arose shall be applied. In accordance with Section 26(1) of the VAT Act, the taxable person or the person liable to pay tax shall convert the required payment in a foreign currency into euros using the ECB or NBS exchange rate (the NBS exchange rate shall be used only if the ECB does not publish an exchange rate) or the exchange rate under customs regulations, and shall subsequently calculate the VAT on the amount in euros. The taxpayer or the person liable to pay tax shall round the calculated tax in euros to the nearest euro cent, rounding down to 0.005 euros and rounding up from 0.005 euros, in accordance with Section 26(3) of the VAT Act.
Primary source: Financial Administration of the Slovak Republic, FAQ 9/VAT/2025/IM k e-invoice, July 2026 update. Processed and checked on 13 July 2026.