# Quantity

Source: https://developer.avalara.com/vat-erp/transactions/certification-requirements/quantity/

**Element type:** Required

**Endpoints/models used:** [LineItemModel](https://developer.avalara.com/api-reference/avatax/rest/v2/models/LineItemModel/)

Your UI must include a method for allowing users to specify the quantity of an item that is passed to AvaTax. Items quantities are specified using the `quantity` field on the [LineItemModel](https://developer.avalara.com/api-reference/avatax/rest/v2/models/LineItemModel/).

This field should be optional for users. If a user doesn't provide a `quantity`, AvaTax will assume the quantity to be 1.

[![Closed](https://avalara-devdocs-prod.mcoutput.com/vat-erp/Skins/Default/Stylesheets/Images/transparent.gif)View example](javascript:void\(0\);)

```
{    ...,  "lines": [    {      "number": "1",      "quantity": 1,      "amount": 100,      "taxCode": "PS081282",      "itemCode": "Y0001",      "description": "Yarn"    }  ],  ...} 
```