E-invoice error explained
The net price of a line (BT-146) must not be below 0.
The net price of a line (BT-146) must not be below 0. A negative line is still possible: the quantity (BT-129) is negative and the price stays positive. The line amount (BT-131) is negative either way.
The Item net price (BT-146) shall NOT be negative.
Source: KoSIT configuration XRechnung 3.0.2 (31 Jan 2026).
Flip the sign: positive price in ram:NetPriceProductTradePrice/ram:ChargeAmount, negative quantity in ram:BilledQuantity. An invoice-wide discount is better written as a document-level allowance. If the whole document credits money, issue a credit note (381) with positive amounts.
Wrong (CII)
<ram:SpecifiedLineTradeAgreement>
<ram:NetPriceProductTradePrice>
<ram:ChargeAmount>-50.00</ram:ChargeAmount>
</ram:NetPriceProductTradePrice>
</ram:SpecifiedLineTradeAgreement>
<ram:SpecifiedLineTradeDelivery>
<ram:BilledQuantity unitCode="C62">1</ram:BilledQuantity>
</ram:SpecifiedLineTradeDelivery>Right (CII)
<ram:SpecifiedLineTradeAgreement>
<ram:NetPriceProductTradePrice>
<ram:ChargeAmount>50.00</ram:ChargeAmount>
</ram:NetPriceProductTradePrice>
</ram:SpecifiedLineTradeAgreement>
<ram:SpecifiedLineTradeDelivery>
<ram:BilledQuantity unitCode="C62">-1</ram:BilledQuantity>
</ram:SpecifiedLineTradeDelivery>Sales / Project Operations: Sales and Project Operations have no e-invoice output out of the box. In the WBS Invoice Accelerator for Dynamics 365 the Accelerator handles this itself: Project Operations writes correction lines as quantity 1 times a negative price, and the Accelerator writes them to the e-invoice as a positive price with a negative quantity. Line amount and totals stay the same.
Check your invoice for free. The validator shows every finding with an explanation and its location in the XML.