# BT-131 Invoice line net amount

The total amount of the invoice line after applying any item-level allowances or charges, but excluding VAT.

> BT-131 (Invoice line net amount) is the post-line-discount, pre-VAT amount for one invoice line. Mandatory under EN 16931. Must equal BT-129 (quantity) × BT-146 (net price) minus any line allowances plus line charges (PEPPOL-EN16931-R120), to two decimals. Example: 100.00.
>
> BT-131 · EN 16931 / XRechnung 3.x

## BT Reference Card

Key EN 16931 and XRechnung facts for this business term.

- **BT code**: BT-131
- **Name**: Invoice line net amount
- **Cardinality**: Mandatory (M)
- **Business group**: BG-25 INVOICE LINE
- **Data type**: Amount
- **Example value**: 100.00
- **Common error**: PEPPOL-EN16931-R120: Invoice line net amount (BT-131) shall equal BT-129 (Quantity) × BT-146 (Item net price) ÷ BT-149 (base quantity), minus line allowances, plus line charges. Validator failures here are usually rounding errors. The sum of all line amounts must also equal BT-106 (BR-CO-10).

## Quick answer

The total amount of the invoice line after applying any item-level allowances or charges, but excluding VAT.

> **Line items**: The goods or services on each invoice line, including quantities, prices, and VAT.

- [Validate XML](/en/xrechnung-validator?source=resource&bt=BT-131)
- [Convert invoice](/en/pdf-to-xrechnung?source=resource&bt=BT-131)

## In plain language

The total amount of the invoice line after applying any item-level allowances or charges, but excluding VAT.

The total amount of the invoice line after applying any item-level allowances or charges, but excluding VAT.

Used to calculate the invoice subtotal (BT-106) by summing all line net amounts.

## What you usually enter here

Decimal number with up to 2 decimal places, non-negative

Typical valid values include: 100.00, 250.50, 0.00

Mandatory for each invoice line according to EN 16931-1.

## What goes wrong often

Avoid values like: -100.00, 100,50, 1.000.00

Relevant rule codes: BR-24, BR-DEC-23, PEPPOL-EN16931-R120, BR-CO-10

## Examples in context

Used to calculate the invoice subtotal (BT-106) by summing all line net amounts.

Mandatory for each invoice line according to EN 16931-1.

## Valid Examples

- 100.00
- 250.50
- 0.00

## Invalid Examples

- -100.00
- 100,50
- 1.000.00

## Related Fields

Used to calculate the invoice subtotal (BT-106) by summing all line net amounts.

- [BT-129 Invoice line quantity](/resources/xrechnung/bt-129-invoice-line-quantity)
- [BT-132 Referenced purchase order line identifier](/resources/xrechnung/bt-132-referenced-purchase-order-line-identifier)
- [BT-133 Invoice line buyer accounting reference](/resources/xrechnung/bt-133-invoice-line-buyer-accounting-reference)
- [BT-134 Invoice line period start date](/resources/xrechnung/bt-134-invoice-line-period-start-date)
- [BT-135 Invoice line period end date](/resources/xrechnung/bt-135-invoice-line-period-end-date)
- [BT-136 Invoice Line Allowance Amount](/resources/xrechnung/bt-136-invoice-line-allowance-amount)
- [BT-106 Sum of Invoice Line Net Amount](/resources/xrechnung/bt-106-sum-of-invoice-line-net-amount)

## XML mapping and field facts

Open the technical reference if you need XML paths, validator rule codes, legal wording, or schema-specific mapping details.

### Field ID:
BT-131

### Data Type:
amount

### Cardinality:
1..1

### Requirement:
Mandatory

### Since Version:
XRechnung 1.0+

## XML Implementation

### UBL 2.1 Syntax
```
/Invoice/cac:InvoiceLine/cbc:LineExtensionAmount
```

### CII (UN/CEFACT) Syntax
```
/CrossIndustryInvoice/SupplyChainTradeTransaction/ApplicableHeaderTradeSettlement/ram:SpecifiedTradeSettlementLineMonetarySummation/ram:LineTotalAmount
```

## Validation Rules

### BR-24
BR-24

### BR-DEC-23
BR-DEC-23

### PEPPOL-EN16931-R120
PEPPOL-EN16931-R120

### BR-CO-10
BR-CO-10

## Check whether your XRechnung sets BT-131 correctly

Upload the XML file to the free validator. It applies the KoSIT rules for XRechnung 3.0 and names each finding with its rule ID, for this field for example BR-24, BR-DEC-23. Creating a new invoice instead? The converter checks the invoice against the same rules and shows the findings before download.

- [Validate XML](/en/xrechnung-validator)
- [Convert invoice](/en/pdf-to-xrechnung)

Free, no account needed. XML file up to 2 MB.

## Why the standard cares about this field

### Business Context
Used to calculate the invoice subtotal (BT-106) by summing all line net amounts.

### Legal Requirement
Mandatory for each invoice line according to EN 16931-1.

## FAQ

### How is the Invoice line net amount (BT-131) calculated?
BT-131 is the line quantity (BT-129) times the net unit price (BT-146, divided by BT-149 base quantity), then minus line allowances (BT-136) and plus line charges (BT-141). It excludes VAT and is expressed in the document currency.

### Why does BT-131 fail a BR-CO consistency check?
BR-CO-10 requires the sum of all BT-131 line amounts to equal the document line total (BT-106). Failures usually come from rounding the price×quantity result differently than the stated BT-131, or omitting a line allowance (BT-136) or charge (BT-141) from the formula.

## Official sources and tools

- [KoSIT Validator](https://erechnungsvalidator.service-bw.de/)
- [XRechnung Standard](https://xeinkauf.de/xrechnung/)
- [Test Suite](https://github.com/itplr-kosit/xrechnung-testsuite)