Which currency, and which exchange rate, a Bulgarian invoice has to use.

The provision

Bulgaria pins the taxable amount as well as the tax.

Most member states that legislate the point pin only the tax figure. Bulgaria's rule, rewritten for the euro, also requires the taxable amount in euro, following the conversion rule of article 26(6).

«Сумите по фактурата могат да бъдат посочени в която и да е валута, при условие че данъчната основа и размерът на данъка се посочат в евро при спазване изискванията на чл. 26, ал. 6.»

The amounts on the invoice may be in any currency, provided the taxable amount and the amount of tax are stated in euro in compliance with art. 26(6).

Art. 114(5), Zakon za danak varhu dobavenata stoynost

When it reaches you

If you sell through the stores, this bites in one case.

Article 230 constrains the amount of VAT payable or to be adjusted. An app developer's ordinary invoice to a store or an ad network carries no VAT amount at all: it is a reverse-charge supply to another member state, or a supply outside the scope entirely. Where there is no tax line, there is nothing for the currency rule to bind. The rule reaches you on a supply that actually charges Bulgaria VAT.

What Ureta does about it

The rate is pinned when the month is, and it is kept with the document.

• The ECB reference rate, for every EU tenant. It is the rate article 91(2) obliges every member state to accept. A currency other than the euro is converted through the euro, as the same article says.
• The rate is pinned per month and stored, so a document issued last March still reports the rate it carried in March rather than a number recomputed today.
• Nothing is guessed. Where no rate from a defensible authority is available for a currency, the engine refuses to issue rather than putting a plausible wrong number on a legal document.