# BT-137 Invoice Line Allowance Base Amount

The base amount used to calculate a percentage allowance at line level.

## Quick answer

The base amount used to calculate a percentage allowance at line level.

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

- validate
- convert

## In plain language

The base amount used to calculate a percentage allowance at line level.

The base amount used to calculate a percentage allowance at line level.

Captures line-level discounts and surcharges so the invoice line net amount can be reconciled from quantity, price, allowances, and charges.

## What you usually enter here

Decimal amount in invoice currency

Typical valid values include: 100.00

Defined by EN 16931 for invoice line allowance and charge details; apply profile cardinality and the listed code list or calculation rules when the element is present.

## What goes wrong often

Avoid values like: -100.00

## Examples in context

Captures line-level discounts and surcharges so the invoice line net amount can be reconciled from quantity, price, allowances, and charges.

Defined by EN 16931 for invoice line allowance and charge details; apply profile cardinality and the listed code list or calculation rules when the element is present.

## Valid Examples

- 100.00

## Invalid Examples

- -100.00

## Related Fields

Captures line-level discounts and surcharges so the invoice line net amount can be reconciled from quantity, price, allowances, and charges.

- [BT-136 Invoice Line Allowance Amount](/resources/xrechnung/bt-136-invoice-line-allowance-amount)
- [BT-138 Invoice Line Allowance Percentage](/resources/xrechnung/bt-138-invoice-line-allowance-percentage)

## 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-137

### Data Type:
amount

### Cardinality:
0..1

### Requirement:
Optional

### Since Version:
Optional

## XML Implementation

### UBL 2.1 Syntax
```
/Invoice/cac:InvoiceLine/cac:AllowanceCharge[cbc:ChargeIndicator=false()]/cbc:BaseAmount
```

## Why the standard cares about this field

### Business Context
Captures line-level discounts and surcharges so the invoice line net amount can be reconciled from quantity, price, allowances, and charges.

### Legal Requirement
Defined by EN 16931 for invoice line allowance and charge details; apply profile cardinality and the listed code list or calculation rules when the element is present.

## 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)