> ## Documentation Index
> Fetch the complete documentation index at: https://docs.mercurjs.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Tax Code Module Links

> Module links for the Tax Code Module

# Links between Tax Code Module and Other Modules

This document showcases the module links defined between the Tax Code Module and other Commerce Modules.

## Summary

The Tax Code Module has the following links to other modules:

| First Data Model | Second Data Model | Type                 | Description                                                         |
| ---------------- | ----------------- | -------------------- | ------------------------------------------------------------------- |
| ProductCategory  | TaxCode           | Stored - many-to-one | Associates product categories with tax codes for tax classification |

***

## Product Module

Mercur defines a link between the Product Module's `ProductCategory` data model and the Tax Code Module's `TaxCode` data model. This allows product categories to be associated with specific tax codes for proper tax calculation and compliance.

### Retrieve with Query

To retrieve the tax code of a product category with Query, pass `tax_code.*` in `fields`:

<Tabs>
  <Tab title="query.graph">
    ```ts theme={null}
    const { data: categories } = await query.graph({
      entity: "product_category",
      fields: [
        "*",
        "tax_code.*",
      ],
    })

    // categories[0].tax_code
    ```
  </Tab>

  <Tab title="useQueryGraphStep">
    ```ts theme={null}
    import { useQueryGraphStep } from "@medusajs/medusa/core-flows"

    // ...

    const { data: categories } = useQueryGraphStep({
      entity: "product_category",
      fields: [
        "*",
        "tax_code.*",
      ],
    })

    // categories[0].tax_code
    ```
  </Tab>
</Tabs>

### Manage with Link

To manage the tax code of a product category, use Link:

<Tabs>
  <Tab title="link.create">
    ```ts theme={null}
    import { Modules } from "@medusajs/framework/utils"

    // ...

    await link.create({
      [Modules.PRODUCT]: {
        product_category_id: "pcat_123",
      },
      taxcode: {
        tax_code_id: "taxc_123",
      },
    })
    ```
  </Tab>

  <Tab title="createRemoteLinkStep">
    ```ts theme={null}
    import { createRemoteLinkStep } from "@medusajs/medusa/core-flows"

    // ...

    createRemoteLinkStep({
      [Modules.PRODUCT]: {
        product_category_id: "pcat_123",
      },
      taxcode: {
        tax_code_id: "taxc_123",
      },
    })
    ```
  </Tab>
</Tabs>