---
products:
  - tax
---

export const metadata = {
  title: `Tax Lines in Cart Module`,
}

# {metadata.title}

In this document, you’ll learn about tax lines in a cart and how to retrieve tax lines with the Tax Module.

## What are Tax Lines?

A tax line indicates the tax rate of a line item or a shipping method. The [LineItemTaxLine data model](/references/cart/models/LineItemTaxLine) represents a line item’s tax line, and the [ShippingMethodTaxLine data model](/references/cart/models/ShippingMethodTaxLine) represents a shipping method’s tax line.

![A diagram showcasing the relation between other data models and the tax line models](https://res.cloudinary.com/dza7lstvk/image/upload/v1711534431/Medusa%20Resources/cart-tax-lines_oheaq6.jpg)

---

## Tax Inclusivity

By default, the tax amount is calculated by taking the tax rate from the line item or shipping method’s amount, and then adding them to the item/method’s subtotal.

However, line items and shipping methods have an `is_tax_inclusive` property that, when enabled, indicates that the item or method’s price already includes taxes.

So, instead of calculating the tax rate and adding it to the item/method’s subtotal, it’s calculated as part of the subtotal.

<Note>

The following diagram is a simplified showcase of how a subtotal is calculated from the taxes perspective.

</Note>

![A diagram showing an example of calculating the subtotal of a line item using its taxes](https://res.cloudinary.com/dza7lstvk/image/upload/v1711535295/Medusa%20Resources/cart-tax-inclusive_shpr3t.jpg)

For example, if a line item's amount is `5000`, the tax rate is `10`, and tax inclusivity is enabled, the tax amount is 10% of `5000`, which is `500`, making the unit price of the line item `4500`.

---

## Retrieve Tax Lines

When using the Cart and Tax modules together, you can use the `getTaxLines` method of the Tax Module’s main service. It retrieves the tax lines for a cart’s line items and shipping methods.

```ts
// retrieve the cart
const cart = await cartModuleService.retrieveCart("cart_123", {
  relations: [
    "items.tax_lines",
    "shipping_methods.tax_lines",
    "shipping_address",
  ],
})

// retrieve the tax lines
const taxLines = await taxModuleService.getTaxLines(
  [
    ...(cart.items as TaxableItemDTO[]),
    ...(cart.shipping_methods as TaxableShippingDTO[]),
  ],
  {
    address: {
      ...cart.shipping_address,
      country_code:
        cart.shipping_address.country_code || "us",
    },
  }
)
```

Then, use the returned tax lines to set the line items and shipping methods’ tax lines:

```ts
// set line item tax lines
await cartModuleService.setLineItemTaxLines(
  cart.id,
  taxLines.filter((line) => "line_item_id" in line)
)

// set shipping method tax lines
await cartModuleService.setLineItemTaxLines(
  cart.id,
  taxLines.filter((line) => "shipping_line_id" in line)
)
```
