# BR-CO-17

> VAT category tax amount (BT-117) = VAT category taxable amount (BT-116) x (VAT category rate (BT-119) / 100), rounded to two decimals.

Checked against Peppol BIS Billing 3.0 2026.5

Canonical: https://einvoicecheck.eu/rules/br-co-17

## Official rule text

VAT category tax amount (BT-117) = VAT category taxable amount (BT-116) x (VAT category rate (BT-119) / 100), rounded to two decimals.

## Why did my invoice fail BR-CO-17?

For each VAT breakdown, the VAT category tax amount (BT-117) must equal the VAT category taxable amount (BT-116) multiplied by the VAT category rate (BT-119) divided by 100, rounded to two decimals. This guarantees each category's VAT is arithmetically consistent with its taxable base and rate.

## Common causes

- Per-category TaxSubtotal/TaxAmount rounded with a different rule (e.g. round-half-down or 4 decimals) than round-half-up to 2 decimals.
- Percent (cbc:Percent) not matching the rate actually used to compute the amount.
- TaxableAmount (BT-116) itself wrong, so the derived VAT is off by more than the allowed rounding tolerance.
- Applying VAT per line and summing, giving a result that differs from taxable-base × rate by more than 0.01.

## How do I fix it?

```
Within each cac:TaxSubtotal, set TaxAmount = round(TaxableAmount × Percent / 100, 2). E.g. 100.00 × 21 / 100 → <cbc:TaxAmount currencyID="EUR">21.00</cbc:TaxAmount> with <cbc:Percent>21</cbc:Percent>.
```