# Using ITaxProviderFactory in Plug-ins

> Learn how to implement a custom tax provider in iDempiere using the ITaxProviderFactory service.

## Goal

The goal of this tutorial is to show how to use the `ITaxProviderFactory` service in your plug-in project. Use the tax provider factory service when you need to provide your own method for calculating taxes on orders, invoices, and RMAs.

## Prerequisites

Before you start, review the following tutorials:

- [Developing Plug-Ins Without Affecting the Core](./developing-plugins)
- [Running Plug-ins Locally in iDempiere](./plugin-running-locally)

## Workflow

After creating the plug-in and setting its dependencies, click on **File > New > Other** and select **Component Definition** from the Plug-in Development section.

Click **Next**. Select your plug-in project (OSGI folder) and choose a file name and a general name. In this example, we used `TaxProviderFactory.xml` and `org.idempierelbr.tax.TaxProviderFactory` for filename/name, but any name works. You don't need to set the class name yet. Click **Finish**.

You will need two classes:

- A `TaxProvider` - a class that implements `ITaxProvider`
- A `TaxProviderFactory` - a class that implements `ITaxProviderFactory`

You only need one `TaxProviderFactory` for all your `TaxProvider` implementations. Create the class `DefaultTaxProvider`, which implements `org.adempiere.model.ITaxProvider`, and implement the inherited abstract methods.

The second class implements `ITaxProviderFactory` and is called `TaxProviderFactory`. In `newTaxProviderInstance()`, check the class name configured in the Tax Provider Configuration window (see below).

![Tax Provider Configuration window](/img/docs/plugin-development/Plugin_ITaxProviderFactory_TPConfigWindow.png)

Open `TaxProviderFactory.xml` and click **Browse** to select the `TaxProviderFactory` class. Add an integer property called `service.ranking` with a positive value (> 0).

On the **Services** tab, add `org.adempiere.base.ITaxProviderFactory` to the **Provided Services** section.

Configure your Client to use the new tax provider.

![Tax Provider Configuration window](/img/docs/plugin-development/Plugin_ITaxProviderFactory_TPConfigWindow.png)

![Tax Provider window](/img/docs/plugin-development/Plugin_ITaxProviderFactory_TPWindow.png)

Configure the Tax Rate to use the tax provider. In this example, we use the Standard tax.
![Tax Rate](/img/docs/plugin-development/Plugin_ITaxProviderFactory_TaxRateWindow.png)

That's the basic setup. To verify it works, add a console log in each method of the `DefaultTaxProvider` class.

Make sure your plug-in is active in the run configurations. Start the client and confirm your plug-in is active. Log in as GardenAdmin/GardenWorld, create a new Sales Order, add some products (set the tax field to Standard), go back to the header, and prepare the order. Check your console log — you should see output from your custom tax provider.

:::tip
Implement each method of `DefaultTaxProvider` to handle taxes for orders, invoices, and RMAs.
:::

## Troubleshooting

- Make sure `TaxProviderFactory.xml` has a unique name (`my.domainname.pluginname.provider.TaxProviderFactory` is a good choice) and that you selected the correct class.
- Make sure your plug-in is activated before you log in.
- Make sure `MANIFEST.MF` contains a `Service-Component:` line with the path to your `TaxProviderFactory.xml` (for example, `Service-Component: TaxProviderFactory.xml`).

This tutorial was contributed by [Alan Lescano](mailto:alan.lesc1@gmail.com) from LBR Localization Brazil.