Amount Calculation
The extension calculates the document totals according to the business rules of EN 16931. The following overview shows how the total terms relate to each other:
Summe der Positionsnettobeträge (BT-106)
+ Summe der Zuschläge auf Belegebene (BT-108)
− Summe der Nachlässe auf Belegebene (BT-107)
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= Steuerbasisbetrag / Nettogesamtbetrag (BT-109)
+ Gesamtbetrag der Umsatzsteuer (BT-110)
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= Bruttogesamtbetrag (BT-112)
− Bereits gezahlter Betrag / Vorauszahlung (BT-113)
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= Fälliger Zahlbetrag (BT-115)
Governing Business Rules
| Rule | Condition |
|---|---|
| BR-CO-13 | BT-109 = BT-106 − BT-107 + BT-108 (tax basis = line sum − allowances + charges) |
| BR-CO-15 | BT-112 = BT-109 + BT-110 (grand total = tax basis + VAT) |
Both of these rules are checked automatically by the verify-amounts command.
Tax Calculation at Document Level
All amounts are carried without tax. VAT is calculated at document level per tax rate from the sum of the line amounts (not summed up per line). As a result, rounding differences may arise compared to line-by-line rounding.
This approach matches the EN 16931 logic, in which VAT is reported as a single amount per tax category/rate (BG-23, "VAT breakdown"). When differences occur, they are usually ≤ 1 cent per tax rate. For guidance on how to handle them, see Support.