# BR-O-09: Charge no VAT in the not subject to VAT breakdown
Amounts outside the scope of VAT carry no tax, so the `cbc:TaxAmount` of a breakdown in category `O` must be zero, with the totals following suit.
- Layer: EN 16931
- Severity: fatal (the document is invalid)
- Topics: VAT, Totals
- Official definition: https://docs.peppol.eu/poacc/billing/3.0/rules/ubl-tc434/BR-O-09/
- Explanation last updated: 2026-09-28
## The short answer
`BR-O-09` fails when a `cac:TaxSubtotal` in category `O` has a `cbc:TaxAmount` other than zero; the recorded invoice charges 5.00, which is 20% of its out-of-scope line of 25.00. Set the breakdown tax amount to `0.00` and take the 5.00 out of `cac:TaxTotal/cbc:TaxAmount`, `cbc:TaxInclusiveAmount` and `cbc:PayableAmount`, which brings the amount due back to 25.00.
If the buyer really owes VAT on the amount, the supply is not outside the scope of VAT. Then the category is what is wrong, and a document that charges VAT cannot be expressed with `O` at all.
## What the rule checks
The rule compares the `cbc:TaxAmount` beside each `O` `cac:TaxCategory` under the `VAT` scheme with zero, as a number: `0` passes as well as `0.00`, and a negative amount fails like a positive one, as -5.00 did when tried.
`BR-CO-17` only catches the larger amounts, because an `O` breakdown normally has no `cbc:Percent`, and for a breakdown without a rate that rule asks only for a tax amount that rounds to zero as a whole number. When tried, 0.40 in the `O` breakdown reported this rule alone, and 0.50 brought `BR-CO-17` back.
The VAT total is compared by a different rule. With 5.00 in the `O` breakdown and the VAT total left at 0.00, the document reported `BR-CO-14` as well as this rule and `BR-CO-17` when tried.
| Term | Meaning | UBL element |
|---|---|---|
| BT-117 | VAT category tax amount | `cac:TaxTotal/cac:TaxSubtotal/cbc:TaxAmount` |
| BT-118 | VAT category code | `cac:TaxTotal/cac:TaxSubtotal/cac:TaxCategory/cbc:ID` |
| BT-110 | Invoice total VAT amount | `cac:TaxTotal/cbc:TaxAmount` |
## How an integration ends up here
Possible causes, from the shape of the rule rather than from measured usage:
- Tax is calculated at the default Standard rate for every breakdown, whatever its category.
- An invoice that used to be Standard rated was moved to `O` by relabelling the category, and the stored tax figures were kept.
- The supplier is not registered for VAT, but its invoicing software was set up with VAT switched on.
- The document VAT is calculated once and then attributed to the only breakdown there is, the `O` one.
## How to fix it
1. Confirm that the amounts in the breakdown are outside the scope of VAT. If they are, no VAT is due on them and the breakdown tax amount is `0.00`.
2. Set `cbc:TaxAmount` in the `O` `cac:TaxSubtotal` to `0.00`.
3. Recalculate the VAT total as the sum of the breakdown tax amounts, then the total with VAT and the amount due: in the recorded example the VAT total falls from 5.00 to 0.00, and both other totals from 30.00 to 25.00.
4. If VAT is due after all, move the lines to the category that applies, with its rate, and replace the `O` breakdown and its reason with that category's breakdown; the VAT identifiers that `BR-O-02` forbade can then return.
## Before and after
These are fragments, not complete documents. The complete synthetic documents they come from are linked below.
Fragment of the failing invoice: 5.00 of VAT in the O breakdown, carried into the totals
```xml
5.00
25.00
5.00
O
VATEX-EU-O
Not subject to VAT
VAT
25.00
25.00
30.00
30.00
```
Fragment of the corrected invoice: no VAT in the O breakdown, and 25.00 due
```xml
0.00
25.00
0.00
O
VATEX-EU-O
Not subject to VAT
VAT
25.00
25.00
25.00
25.00
```
The failing invoice shows 5.00 as the `O` breakdown tax amount and as the VAT total, and 30.00 as `cbc:TaxInclusiveAmount` and `cbc:PayableAmount`; the corrected invoice has 0.00 and 25.00. Beside `BR-O-09`, the failing document reports `BR-CO-17`: with no rate in the `O` breakdown, that rule expects the tax amount to round to 0, and 5.00 does not.
### What the validator reported
- The failing invoice reports [BR-CO-17](https://ironfang.com/docs/finance/rules/BR-CO-17.md) and **BR-O-09**. The corrected document passes every layer with no findings.
- [Download the failing XML](https://ironfang.com/finance/rule-examples/BR-O-09-invalid.xml)
- [Download the corrected XML](https://ironfang.com/finance/rule-examples/not-subject-valid.xml)
Recorded on phive 12.1.0 / phive-rules-peppol 4.5.6 / Saxon-HE 12.10, the engine behind the free validator, using synthetic data. A recorded result is regression evidence for these documents; it is not a certification.
## Where it applies
- Applies to UBL `Invoice` and `CreditNote`; as a credit note the failing invoice reported this rule and `BR-CO-17` again when tried.
- Only `O` breakdowns under the `VAT` scheme are tested. The Zero rated, exempt, reverse-charge, intra-community and export categories each have a nil tax amount rule of their own.
- The breakdown's other values are checked elsewhere: its taxable amount by `BR-O-08` and its reason by `BR-O-10`.
## Related rules
- [BR-CO-17 is reported with this rule, and only flags an O tax amount that does not round to zero](https://ironfang.com/docs/finance/rules/BR-CO-17.md)
- [BR-O-08 checks the taxable amount of the same O breakdown](https://ironfang.com/docs/finance/rules/BR-O-08.md)
- [BR-E-09 is the zero tax amount rule for exempt breakdowns](https://ironfang.com/docs/finance/rules/BR-E-09.md)
- [BR-O-01 requires this breakdown to appear exactly once](https://ironfang.com/docs/finance/rules/BR-O-01.md)
## Scope and source
Written for Peppol BIS Billing 3.0.21 (May 2026), EN 16931 1.3.16, as applied to UBL 2.1 Invoice and CreditNote documents. Other profiles, syntaxes and releases can define this identifier differently. Guidance version 2026-09-28.1: source checked 2026-09-28, explanation last updated 2026-09-28.
[The official definition of BR-O-09](https://docs.peppol.eu/poacc/billing/3.0/rules/ubl-tc434/BR-O-09/) carries the normative wording and test. This page is our explanation of it, not a copy.
Guidance does not change the engine verdict. Fixing this finding does not mean the document passes every layer, and validation does not certify legal or tax compliance or transmit a document over Peppol.
## Links
- [This rule as a web page](https://ironfang.com/docs/finance/rules/BR-O-09)
- [Free Peppol invoice validator](https://ironfang.com/tools/peppol-validator)
- [Rule index](https://ironfang.com/docs/finance/rules.md)
- [Ironfang Finance API docs](https://ironfang.com/docs/finance)
- The same rule is available to MCP clients as the tool `finance.rule.get` on https://mcp.ironfang.com/mcp