# BR-DEC-09 Sum of Invoice line net amount must not exceed two decimal places

The BT-106 Sum of Invoice line net amount is limited to a maximum of two decimal places. Any value carrying three or more fractional digits fails EN16931 validation.

## Problem Description

The BT-106 Sum of Invoice line net amount is limited to a maximum of two decimal places. Any value carrying three or more fractional digits fails EN16931 validation.

> **ERROR**: XRechnung 3.0

## Context and Significance

This is an EN16931 core decimal-precision constraint enforced by KoSIT: every monetary amount in the invoice must be expressed with no more than two decimals.

## Solution

Round BT-106 to two decimal places before serialising the amount, and apply the same rounding used in the BR-CO total and sum calculations so the invoice still reconciles.

- validate
- convert

## Valid Examples

- BT-106 = 1000.00 — two decimals accepted

## Invalid Examples

- BT-106 = 1000.000 — three decimals rejected

## Code Examples

### Valid XML
```
<cac:LegalMonetaryTotal>
  <cbc:LineExtensionAmount currencyID="EUR">1000.00</cbc:LineExtensionAmount>
</cac:LegalMonetaryTotal>
```

### Invalid XML
```
<cac:LegalMonetaryTotal>
  <cbc:LineExtensionAmount currencyID="EUR">1000.000</cbc:LineExtensionAmount>
</cac:LegalMonetaryTotal>
```

## Affected Fields

- [BT-106 Sum of Invoice line net amount](/resources/xrechnung/bt-106-sum-of-invoice-line-net-amount)

## Related Rules

- [BR-CO-10](/resources/kosit-validator-errors/br-co-10-sum-of-line-net-amounts-must-equal-line-total)

## Validation Tools

- [Official KoSIT Validator](https://erechnungsvalidator.service-bw.de/): Validate your XRechnung files against all BR-DE rules.
- [Convert PDF to XRechnung](/pdf-to-xrechnung): Automatic validation error fixes when converting.

## Related Resources

- [Official Specification](https://xeinkauf.de/xrechnung/)
- [Test Suite](https://github.com/itplr-kosit/xrechnung-testsuite)
- [Complete Error List](/resources/kosit-validator-errors): Overview of all German XRechnung validation rules.