Key takeaways
- An invoice may show its amounts in any currency, but the VAT amount payable must be expressed in euros.
- The rule comes from Article 230 of the VAT Directive 2006/112/EC; the exchange rate comes from Article 91.
- The applicable rate is the one in force when VAT becomes chargeable, in practice the European Central Bank rate.
- An e-invoice carries two currencies through EN 16931: document currency (BT-5) and VAT accounting currency (BT-6).
Invoicing in a foreign currency without getting VAT wrong
You sell to a client in the United States, the United Kingdom or Switzerland, and the contract is denominated in dollars, pounds or Swiss francs. The question that comes up on the very first foreign-currency invoice is simple: which currency should VAT be shown in? The answer does not depend on commercial custom but on a precise rule, the same across the European Union.
The principle fits in one sentence: the amounts on an invoice may be expressed in any currency, provided that the VAT amount payable is expressed in euros. That is Article 230 of Directive 2006/112/EC, the common basis of European VAT. For a Belgian business, the national currency is the euro: VAT must therefore appear in euros, whatever currency the rest of the invoice uses.
This article explains what the rule actually requires, which exchange rate to use, and how a structured e-invoice carries both currencies cleanly, without re-keying.
VAT must be expressed in euros
The freedom of currency stops at the VAT amount. Article 230 is explicit: the VAT amount payable or to be adjusted must appear in the national currency of the Member State where the tax is due. The reason is as practical as it is legal: the tax authority collects and audits VAT in euros, from your returns filed in euros. A tax amount stated only in dollars would be unusable for the periodic return.
In practice, the rest of the invoice may stay in the contract currency: unit price, quantities, total excluding VAT, total payable. Only the VAT amount must be paired with a value in euros. Nothing prevents you from also converting the other totals as a courtesy to the client, but the rule requires only the conversion of the tax.
| May stay in foreign currency | Must be in euros | |
|---|---|---|
| Line unit price and quantities | ||
| Total excluding VAT | ||
| VAT amount payable | ||
| Total including VAT |
This obligation combines with the other mandatory invoice details in Belgium: converting VAT does not exempt you from them, it adds to them. A foreign-currency invoice is still a Belgian invoice subject to the same formal rules.
The exchange rate to use
That leaves the rate. Converting VAT into euros requires a clear rule, otherwise two businesses would report different figures for the same transaction. Article 91 of Directive 2006/112/EC settles it: the applicable rate is the one in force at the time VAT becomes chargeable, not the rate on the day of payment or collection.
For that rate, the directive provides that Member States accept the latest exchange rate published by the European Central Bank at the time the tax becomes chargeable. This is a single, public, verifiable reference, which removes any argument about the source of the rate. The moment of chargeability itself depends on the nature of the transaction and follows the usual Belgian VAT rules.
Getting the VAT conversion right
Identify the moment of chargeability
This is the date that fixes the exchange rate, not the payment date.
Take the reference rate
The latest rate published by the European Central Bank at that time.
Apply the rate to the VAT amount only
The conversion covers the tax due; the other amounts follow the contract.
Keep a record of the rate used
Useful in an audit: the rate and its date justify the euro amount.
This point is often underestimated. Taking the rate on the payment date rather than at chargeability can distort the VAT amount reported, especially on volatile currencies. The chargeability rule exists precisely to anchor the conversion to an objective date.
How an e-invoice handles two currencies
This is where the structured invoice shows its value. On a PDF, showing VAT in euros next to a total in dollars is a matter of manual layout, with the risk of omission that implies. An invoice compliant with the EN 16931 standard treats the two currencies as separate data, readable by software.
The standard provides two dedicated fields. The document currency (BT-5) carries the invoicing currency. The VAT accounting currency (BT-6) states the currency in which the tax is accounted for, the euro in Belgium. When these two currencies differ, a third element comes into play: the invoice total VAT amount in accounting currency (BT-111), which carries the VAT converted into euros. The link with the rule is direct: BT-111 applies the conversion mechanism of Article 91.
document currency
the currency you invoice in
VAT currency
the euro for a Belgian business
converted VAT
the VAT amount in the accounting currency
The Peppol BIS Billing 3.0 profile reuses this mechanism unchanged: when the document currency differs from the VAT accounting currency, the VAT amount in euros must be provided in the dedicated field. The profile does not validate the exchange rate you applied — that responsibility stays yours — but it requires the euro value to be present so that the recipient and the tax authority have a usable amount. For the structure of the file that carries these fields, see the UBL 2.1 format explained.
Compliant foreign-currency invoices, VAT in euros included
YouInv handles the document currency and the VAT conversion to euros on your Peppol BIS invoices, with no re-keying or manual calculation.
What this changes for your business
The right reflex is not to calculate the conversion by hand on each invoice, but to choose a tool that carries it natively. Compliant invoicing software applies the rate at the date of chargeability, fills in the document currency and the VAT accounting currency, and writes the VAT amount in euros into the right field of the e-invoice. Your role is limited to invoicing in the contract currency.
What changes is the criterion for selecting the tool. If you invoice outside the euro area regularly, your solution must be able to handle two currencies on a single document and produce a valid structured invoice, not just a PDF where VAT in euros was added by hand. That is the first thing to check when choosing or updating your software.
Further reading
- Mandatory invoice details in Belgium: the formal framework within which the VAT conversion sits.
- The EN 16931 standard explained: the semantic model that defines the currency fields.
- Intra-EU VAT: the rules for invoicing between businesses in the European Union.
The reference sources prevail: Directive 2006/112/EC (Articles 230 and 91) on EUR-Lex, and the Peppol BIS Billing 3.0 documentation published by OpenPeppol.
Can you issue an invoice in a foreign currency in Belgium?
Yes. An invoice may show its amounts in any currency. The only constraint is that the VAT amount payable must also be expressed in euros, the national currency, under Article 230 of the VAT Directive 2006/112/EC.
Does VAT have to appear in euros on a foreign-currency invoice?
Yes. Article 230 of Directive 2006/112/EC requires the VAT amount due to be expressed in the national currency of the Member State where the tax is due, which is the euro in Belgium. The other amounts (line items, total excluding VAT) may stay in the foreign currency.
Which exchange rate should you use to convert VAT into euros?
Article 91 of the VAT Directive sets the mechanism: the applicable rate is the one in force at the time VAT becomes chargeable. Member States accept the latest exchange rate published by the European Central Bank at that time. That rate is used to convert the VAT amount into euros.
How does a Peppol e-invoice handle two currencies?
The EN 16931 standard provides two fields: the document currency (BT-5) for the invoiced amounts and the VAT accounting currency (BT-6). When they differ, the invoice total VAT amount in accounting currency (BT-111) carries the VAT converted into euros. Peppol BIS Billing 3.0 reuses this mechanism.
Do you have to convert every amount on the invoice into euros?
No. Only the VAT amount payable must be expressed in euros. Line prices, the total excluding VAT and the total payable may stay in the foreign contract currency. Converting everything is possible but is not required by the VAT conversion rule.
