PEPPOL-EN16931-R055: Both VAT totals must have the same sign

What it means

When a Peppol invoice gives the VAT total both in the invoice currency (BT-110) and in the VAT accounting currency (BT-111), both must be positive, both negative or both zero.

Why it matters

Peppol BIS Billing 3.0 adds this rule to EN 16931 so that every access point and receiver can process the invoice the same way. The sending or receiving access point rejects an invoice that fails it, so it never reaches the buyer.

How to fix it

Check the conversion of the VAT into the accounting currency: a converted amount keeps the sign of the original. A negative and a positive figure usually mean a credit note was converted as an invoice or the other way round.

The rule as published

Invoice total VAT amount and Invoice total VAT amount in accounting currency MUST have the same operational sign

Where this rule applies