For tax to be assessed and charged for a particular account on a particular service, you must follow the below prerequisites.
Complete Tax Prerequisites
Overview
Prerequisites
For any third-party tax engine to work, you must open a ticket with Aria Customer Support 
to enable the following batch jobs to run every day:
- Standard tax post: post to external tax server
- Standard tax requeue: requeue failed tax posts
You must also create a new tax service. Follow the steps below for instructions.
Getting Here: Click Products > Services > New
- You must select Yes from the Taxable drop-down when creating or editing the service.
- You must have one or more countries configured in your Aria environment.
- The account address, billing address, or statement address on the account must be in a jurisdiction for which you have configured taxes.
Note: If a customer consumes a taxable service, but does not reside in a jurisdiction for which taxes have been configured, that customer will not be charged taxes, even if the service consumed has been marked as “taxable." If a customer resides in a jurisdiction for which taxes have been configured, and has consumed a service that is not marked as “taxable,” no taxes will be charged for that service.