# 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 (BR-CO-4), to two decimals. Example: 100.00.
>
> BT-131 · EN 16931 / XRechnung 3.x

## BT Reference Card

Canonical EN 16931 / XRechnung facts for this business term — citable from this anchor.

- **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**: BR-CO-4: Invoice line net amount (BT-131) shall equal BT-129 (Quantity) × BT-146 (Item net price), minus line allowances, plus line charges. Validator failures here are usually rounding errors.

## 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.

## 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-2, BR-DEC-07

## 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 net price](/resources/xrechnung/bt-136-invoice-line-net-price)
- [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-2
BR-2

### BR-DEC-07
BR-DEC-07

## 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.

## Official sources and tools

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