# Invoice lines

Source: https://developer.avalara.com/avatax-dm-combined-erp/sales-tax-badge/transactions/invoice-lines/

# Invoice lines

To accurately calculate tax, you’ll need to provide some details about what is being sold. There are a number of options that you can provide (refer to the [LineItemModel API](https://developer.avalara.com/api-reference/avatax/rest/v2/models/LineItemModel/)), but at minimum you will need to send the details of one line item.

-   `number`: AvaTax automatically numbers lines on your invoice starting with 1. If you prefer to use your own line numbers, please specify them in this value.
-   `quantity`: This is the quantity of goods or services being sold. Note that this value does not affect any totals; to determine the price-per-each, divide the `amount` value by the `quantity` value. If you do not provide `quantity`, the value will be assumed to be 1. Although this field is optional, some taxes are affected by dollar-amount thresholds and caps per item, and AvaTax uses the `quantity` and `amount` values to calculate this correctly. We strongly recommend providing the correct `quantity` for each line. In addition, the `quantity` must be a positive value.
-   `amount`: This is the total price of goods or services for this line item. This is the total, fully extended value. For example, if you specify a `quantity` of 2 and an `amount` of 10, this means that you have sold two $5 items for a total price of $10. The `amount` can be a positive value for sales transactions or a negative value for refund transactions. The `amount` can also be 0.
-   `taxCode`: This is how you specify the type of good or service that is being sold. If you omit the `taxCode` value, AvaTax defaults to treating the item as taxable Tangible Personal Property using the tax code `P0000000`.
-   `addresses`: Each invoice line can have its own custom addresses. If we make one sale that includes multiple separate shipments, we can attach the correct address to each line. If the `addresses` field on a line is null or missing, the line will be assumed to use the `addresses` from the document level; but if the value is non-null, the line will have its own custom `addresses` and will not inherit any `addresses` from the document level.

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