| Key | key | cbc.Key | | Key for grouping or identifying charges for tax purposes. A suggested list of keys is provided, but these are for reference only and may be extended by the issuer. |
| Code | code | cbc.Code | | Reference or ID for this charge defined by the issuer |
| Reason | reason | string | | Text description as to why the charge was applied |
| Base | base | num.Amount | | Base for percent calculations instead of the line’s sum |
| Percent | percent | num.Percentage | | Percentage of base or parent line’s sum |
| Quantity | quantity | num.Amount | | Quantity of units to apply the charge to when using the rate instead of the line’s quantity. |
| Unit | unit | org.Unit | | Unit to associate with the quantity when using the rate. |
| Rate | rate | num.Amount | | Rate defines a price per unit to use instead of the percentage. |
| Amount | amount | num.Amount | | Fixed or resulting charge amount to apply (calculated if percent present). |
| Extensions | ext | tax.Extensions | | Extension codes that apply to the charge |
