CII-SR-131: Remove the exchange rate from the unit price discount

What it means

On each line, the unit price before discount (BT-148) can carry one discount (BT-147). This rule checks that this discount holds no ActualTradeCurrencyExchange block, which would give an exchange rate for the discount. The discount amount itself is allowed.

Why it matters

An EN 16931 invoice states its amounts in one invoice currency, so an exchange rate on a single discount has no place in it and may be ignored. The file is still accepted, because this is a warning. It is worth fixing for a clean file, and worth a second look if the discount was meant to be converted from another currency.

How to fix it

Delete the ActualTradeCurrencyExchange block from the AppliedTradeAllowanceCharge under GrossPriceProductTradePrice in the line. Check that the discount amount (ActualAmount) is already in the invoice currency. If your software writes the block, look for an export setting for EN 16931, XRechnung or Peppol BIS, or ask the supplier to stop adding it.

The rule as published

ActualTradeCurrencyExchange should not be present

Where this rule applies