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Integrating AvaTax with Aphix WebShop

Purpose and scope

Current support

Integration between WebShop and Avalara AvaTax so that tax calculations can be carried out for retail and complex sales tax calculations.

It is assumed that you already have an Avalara account set up.

Avalara AvaTax is tax calculation software used to calculate tax owed on products sold. It is a cloud-based software that regularly applies updated rates based on location, legislation, tax regulations, item taxability and more. Our integration with AvaTax provides your customers a seamless checkout process, with relevant sales tax applied to their carts.

The purpose of this feature guide is to describe how the integration works, and how to configure it. For more information on its impact to your customer’s checkout flow when it is configured, read Checkout (USA and Canada).


Key benefits are:

  • Compliance with tax legislation and regulations in United States of America and Canada

  • When active, provides a seamless and integrated sales tax calculation for customers as they place their orders in United States of America and Canada.

Introducing terms and concepts used in this article




(API), which is an interface that allows two different computer systems interact with each other. It consists of a number of rules (also known as endpoints) that request data from the other system and receive and process responses from that system.


a client of the merchant.


a client of Experlogix or Aphix; a company who uses the Aphix or Digital Commerce platform.

Sales tax

generic term used to cover the additional tax applied to products in a B2C context. It refers to VAT in the UK and EU, GST in Australia and New Zealand and federal and state tax applied to product sales in USA and Canada.

Product tax code

a classification that the merchant assigns to each product to allow a tax calculation engine calculate the correct sales tax to apply to an order.

Web service

service that allows two disparate systems communicate with each other via a standard messaging system.

Fitting it all together

Avalara AvaTax is tax calculation software used to calculate tax owed on products sold.

Avalara must be installed via the App Store. This is a two step process, where you create a link between WebShop and Avalara with relevant information and then activate the link. Once both these steps are complete, a web service is created that allows the transfer of relevant data between Avalara AvaTax and WebShop. The web service consists of a number of API calls (endpoints) that request and retrieve specific information as needed during your customer’s checkout process. When active, Avalara AvaTax acts as the tax calculations engine during checkout for transactions made in the United States of America (USA) and Canada.

During checkout, WebShop uses API calls to send product information which AvaTax uses to carry out tax calculations. AvaTax returns the result of these tax calculations, which are then displayed on WebShop. The information that is sent to AvaTax is dependent on where certain data is stored; in particular, whether you have product tax codes stored in Avalara or Management Interface. The product tax code is an alphanumeric text string that identifies an item as being part of a set of items; for example, Lumber - solid wood product has a product tax code of PA3000400. You can store the product tax code in either Avalara or upload them to our platform, where they are displayed on the tax codes screen in Management Interface. The product tax code screen is only visible and available to use once the web service between Avalara and WebShop has been established. The web service does not have to active for the product tax code screen to be visible and available for your use.

During checkout, an API call sends product and product tax code data (if it exists) from WebShop to AvaTax. If [product] tax codes are only stored in Avalara, then only product data is sent from WebShop to AvaTax. AvaTax performs appropriate tax calculations and returns the applicable tax, which is displayed in WebShop as part of the checkout process.

When installed and active, Avalara is the source of truth for tax calculations.



External site: AvaTax: Sales Tax Calculation Software - Avalara

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