# BR-AG-09 IPSI VAT amount must equal base times rate

The VAT category tax amount (BT-117) in a VAT breakdown (BG-23) where VAT category code (BT-118) is "IPSI" shall equal the VAT category taxable amount (BT-116) multiplied by the VAT category rate (BT-119).

## Problem Description

The VAT category tax amount (BT-117) in a VAT breakdown (BG-23) where VAT category code (BT-118) is "IPSI" shall equal the VAT category taxable amount (BT-116) multiplied by the VAT category rate (BT-119).

> **ERROR**: XRechnung 3.0

## Context and Significance

The IPSI category (the indirect tax of Ceuta and Melilla) comes from the updated EN16931 code lists supported by the current XRechnung 3.0.2 rulepack; this rule guarantees the declared IPSI VAT amount matches the base and rate exactly.

## Solution

Compute BT-117 as BT-116 × BT-119 ÷ 100 (rounded to two decimals) and write it into the "M" (IPSI) cac:TaxSubtotal/cbc:TaxAmount, e.g. 100.00 × 10.00 % = 10.00.

- validate
- convert

## Valid Examples

- BT-116 = 100.00, BT-119 = 10.00, BT-117 = 10.00

## Invalid Examples

- BT-116 = 100.00, BT-119 = 10.00, but BT-117 = 5.00

## Code Examples

### Valid XML
```
<cac:TaxSubtotal>
  <cbc:TaxableAmount currencyID="EUR">100.00</cbc:TaxableAmount>
  <cbc:TaxAmount currencyID="EUR">10.00</cbc:TaxAmount>
  <cac:TaxCategory>
    <cbc:ID>M</cbc:ID>
    <cbc:Percent>10.00</cbc:Percent>
  </cac:TaxCategory>
</cac:TaxSubtotal>
```

### Invalid XML
```
<cac:TaxSubtotal>
  <cbc:TaxableAmount currencyID="EUR">100.00</cbc:TaxableAmount>
  <cbc:TaxAmount currencyID="EUR">5.00</cbc:TaxAmount>
  <cac:TaxCategory>
    <cbc:ID>M</cbc:ID>
    <cbc:Percent>10.00</cbc:Percent>
  </cac:TaxCategory>
</cac:TaxSubtotal>
```

## Affected Fields

- [BT-117 VAT category tax amount](/resources/xrechnung/bt-117-vat-category-tax-amount)
- [BT-116 VAT category taxable amount](/resources/xrechnung/bt-116-vat-category-taxable-amount)
- [BT-119 VAT category rate](/resources/xrechnung/bt-119-vat-category-rate)

## Related Rules

- [BR-AG-08](/resources/kosit-validator-errors/br-ag-08-ipsi-taxable-amount-equals-sum)
- [BR-AG-01](/resources/kosit-validator-errors/br-ag-01-ipsi-vat-breakdown-required)

## 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.