> ## Documentation Index
> Fetch the complete documentation index at: https://gobl-cli-install-gobl-dev.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Combo

Combo represents the tax combination of a category code and rate key.

## Schema ID

`https://gobl.org/draft-0/tax/set#/$defs/Combo`

## Properties

| Title | Property | Type | Description |
| - | - | - | - |
| Category | `cat` | [cbc.Code](/draft-0/cbc/code) | Tax category code from those available inside a region. |
| Country | `country` | [l10n.TaxCountryCode](/draft-0/l10n/tax_country_code) | Country code override when issuing with taxes applied from different countries. |
| | `key` | [cbc.Key](/draft-0/cbc/key) | Key helps determine the tax situation within the category. |
| Rate | `rate` | [cbc.Key](/draft-0/cbc/key) | Rate within a category and for a given key to apply. |
| Percent | `percent` | [num.Percentage](/draft-0/num/percentage) | Percent defines the percentage set manually or determined from the key. A nil percent implies that this tax combo is either exempt or not-subject. |
| Surcharge | `surcharge` | [num.Percentage](/draft-0/num/percentage) | Some countries require an additional surcharge (may be determined if key present). |
| Extensions | `ext` | [tax.Extensions](/draft-0/tax/extensions) | Local codes that apply for a given rate or percentage that need to be identified and validated. |

## Validation Rules

| Field | Test | Validation Code / Message |
| - | - | - |
| <small>Combo</small> | <ul class="gobl-test"><li>Category in regime</li></ul> | `GOBL-TAX-COMBO-01`<br />Tax category not valid for regime |
| <small>Combo</small> | <ul class="gobl-test"><li>Key in category</li></ul> | `GOBL-TAX-COMBO-02`<br />Tax combo key not valid for category in regime |
| <small>Combo</small> | <ul class="gobl-test"><li>Rate in key</li></ul> | `GOBL-TAX-COMBO-03`<br />Tax combo rate not valid for key in regime |
| <small>Combo</small> | <ul class="gobl-test"><li>Percent valid for key</li></ul> | `GOBL-TAX-COMBO-04`<br />Tax combo percent required or invalid for key in regime |
| <small>Combo</small> | <ul class="gobl-test"><li>Surcharge requires percent</li></ul> | `GOBL-TAX-COMBO-05`<br />Tax combo surcharge requires percent in regime |
| <small>Combo</small> | <ul class="gobl-test"><li>Extension keys defined</li></ul> | `GOBL-TAX-COMBO-06`<br />Tax combo extension key not defined in regime |


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