---
displayed_sidebar: homepage
---

import ParameterTypes from "@site/src/components/ParameterTypes"

# AbstractTaxCalculationStrategy

## Overview

A tax calculation strategy is used to calculate taxes when calculating a cart's totals. The Medusa
backend provides a tax calculation strategy that handles calculating the taxes, taking into account the
defined tax rates and settings such as whether tax-inclusive pricing is enabled.

You can override the tax calculation strategy to implement different calculation logic or to
integrate a third-party service that handles the tax calculation. You can override it either
in a Medusa backend setup or in a plugin.

A tax calculation strategy should be defined in a TypeScript or JavaScript file created under the `src/strategies` directory.
The class must also implement the `ITaxCalculationStrategy` interface imported from the `@medusajs/medusa` package.

For example, you can create the file `src/strategies/tax-calculation.ts` with the following content:

```ts title="src/strategies/tax-calculation.ts"
import {
  ITaxCalculationStrategy,
  LineItem,
  LineItemTaxLine,
  ShippingMethodTaxLine,
  TaxCalculationContext,
} from "@medusajs/medusa"

class TaxCalculationStrategy
  implements ITaxCalculationStrategy {

  async calculate(
    items: LineItem[],
    taxLines: (ShippingMethodTaxLine | LineItemTaxLine)[],
    calculationContext: TaxCalculationContext
  ): Promise<number> {
    throw new Error("Method not implemented.")
  }

}

export default TaxCalculationStrategy
```

---

## constructor

You can use the `constructor` of your tax calculation strategy to access the different services in Medusa through dependency injection.

You can also use the constructor to initialize your integration with the third-party provider. For example, if you use a client to connect to the third-party provider’s APIs, you can initialize it in the constructor and use it in other methods in the service.
Additionally, if you’re creating your tax calculation strategy as an external plugin to be installed on any Medusa backend and you want to access the options added for the plugin, you can access it in the constructor.

### Example

```ts
import {
  ITaxCalculationStrategy,
  LineItemService,
} from "@medusajs/medusa"

type InjectedDependencies = {
  lineItemService: LineItemService
}

class TaxCalculationStrategy
  implements ITaxCalculationStrategy {

  protected readonly lineItemService_: LineItemService

  constructor({ lineItemService }: InjectedDependencies) {
    this.lineItemService_ = lineItemService
  }

  // ...
}

export default TaxCalculationStrategy
```

### Parameters

<ParameterTypes parameters={[{"name":"container","type":"`Record<string, unknown>`","description":"An instance of `MedusaContainer` that allows you to access other resources, such as services, in your Medusa backend.","optional":false,"defaultValue":"","expandable":false,"children":[]},{"name":"config","type":"`Record<string, unknown>`","description":"If this tax calculation strategy is created in a plugin, the plugin's options are passed in this parameter.","optional":true,"defaultValue":"","expandable":false,"children":[]}]} expandUrl="https://docs.medusajs.com/development/entities/repositories#retrieving-a-list-of-records" sectionTitle="new AbstractTaxCalculationStrategy"/>

___

## Properties

<ParameterTypes parameters={[{"name":"container","type":"`Record<string, unknown>`","description":"An instance of `MedusaContainer` that allows you to access other resources, such as services, in your Medusa backend.","optional":false,"defaultValue":"","expandable":false,"children":[]},{"name":"manager_","type":"`EntityManager`","description":"","optional":false,"defaultValue":"","expandable":false,"children":[]},{"name":"transactionManager_","type":"`undefined` \\| `EntityManager`","description":"","optional":false,"defaultValue":"","expandable":false,"children":[]},{"name":"__container__","type":"`any`","description":"","optional":false,"defaultValue":"","expandable":false,"children":[]},{"name":"config","type":"`Record<string, unknown>`","description":"If this tax calculation strategy is created in a plugin, the plugin's options are passed in this parameter.","optional":true,"defaultValue":"","expandable":false,"children":[]},{"name":"__configModule__","type":"`Record<string, unknown>`","description":"","optional":true,"defaultValue":"","expandable":false,"children":[]},{"name":"__moduleDeclaration__","type":"`Record<string, unknown>`","description":"","optional":true,"defaultValue":"","expandable":false,"children":[]}]} expandUrl="https://docs.medusajs.com/development/entities/repositories#retrieving-a-list-of-records" sectionTitle="AbstractTaxCalculationStrategy"/>

___

## Accessors

### activeManager\_

#### Returns

<ParameterTypes parameters={[{"name":"EntityManager","type":"`EntityManager`","optional":false,"defaultValue":"","description":"","expandable":false,"children":[]}]} expandUrl="https://docs.medusajs.com/development/entities/repositories#retrieving-a-list-of-records" sectionTitle="activeManager_"/>

___

## Methods

### calculate

This method calculates the tax amount for a given set of line items under applicable
tax conditions and calculation contexts.

This method is used whenever taxes are calculated. If automatic tax calculation is disabled in a region,
then it's only triggered when taxes are calculated manually as explained in
[this guide](https://docs.medusajs.com/modules/taxes/storefront/manual-calculation).

#### Example

An example of the general implementation of this method in the Medusa backend's tax calculation strategy:

```ts
async calculate(
  items: LineItem[],
  taxLines: (ShippingMethodTaxLine | LineItemTaxLine)[],
  calculationContext: TaxCalculationContext
): Promise<number> {
  const lineItemsTaxLines = taxLines.filter(
    (tl) => "item_id" in tl
  ) as LineItemTaxLine[]
  const shippingMethodsTaxLines = taxLines.filter(
    (tl) => "shipping_method_id" in tl
  ) as ShippingMethodTaxLine[]

  const lineItemsTax = this.calculateLineItemsTax(
    items,
    lineItemsTaxLines,
    calculationContext
  )

  const shippingMethodsTax = this.calculateShippingMethodsTax(
    calculationContext.shipping_methods,
    shippingMethodsTaxLines
  )

  return Math.round(lineItemsTax + shippingMethodsTax)
}
```

#### Parameters

<ParameterTypes parameters={[{"name":"items","type":"[LineItem](../../entities/classes/entities.LineItem.mdx)[]","description":"The line items to calculate the tax total for.","optional":false,"defaultValue":"","expandable":false,"children":[{"name":"id","type":"`string`","description":"The line item's ID","optional":false,"defaultValue":"","expandable":false,"children":[]},{"name":"created_at","type":"`Date`","description":"The date with timezone at which the resource was created.","optional":false,"defaultValue":"","expandable":false,"children":[]},{"name":"updated_at","type":"`Date`","description":"The date with timezone at which the resource was updated.","optional":false,"defaultValue":"","expandable":false,"children":[]},{"name":"cart_id","type":"`string`","description":"The ID of the cart that the line item may belongs to.","optional":false,"defaultValue":"","expandable":false,"children":[]},{"name":"cart","type":"[Cart](../../entities/classes/entities.Cart.mdx)","description":"The details of the cart that the line item may belongs to.","optional":false,"defaultValue":"","expandable":true,"children":[]},{"name":"order_id","type":"`null` \\| `string`","description":"The ID of the order that the line item may belongs to.","optional":false,"defaultValue":"","expandable":false,"children":[]},{"name":"order","type":"[Order](../../entities/classes/entities.Order.mdx)","description":"The details of the order that the line item may belongs to.","optional":false,"defaultValue":"","expandable":true,"children":[]},{"name":"swap_id","type":"`string`","description":"The ID of the swap that the line item may belong to.","optional":false,"defaultValue":"","expandable":false,"children":[]},{"name":"swap","type":"[Swap](../../entities/classes/entities.Swap.mdx)","description":"The details of the swap that the line item may belong to.","optional":false,"defaultValue":"","expandable":true,"children":[]},{"name":"claim_order_id","type":"`string`","description":"The ID of the claim that the line item may belong to.","optional":false,"defaultValue":"","expandable":false,"children":[]},{"name":"claim_order","type":"[ClaimOrder](../../entities/classes/entities.ClaimOrder.mdx)","description":"The details of the claim that the line item may belong to.","optional":false,"defaultValue":"","expandable":true,"children":[]},{"name":"tax_lines","type":"[LineItemTaxLine](../../entities/classes/entities.LineItemTaxLine.mdx)[]","description":"The details of the item's tax lines.","optional":false,"defaultValue":"","expandable":true,"children":[]},{"name":"adjustments","type":"[LineItemAdjustment](../../entities/classes/entities.LineItemAdjustment.mdx)[]","description":"The details of the item's adjustments, which are available when a discount is applied on the item.","optional":false,"defaultValue":"","expandable":true,"children":[]},{"name":"title","type":"`string`","description":"The title of the Line Item.","optional":false,"defaultValue":"","expandable":false,"children":[]},{"name":"description","type":"`null` \\| `string`","description":"A more detailed description of the contents of the Line Item.","optional":false,"defaultValue":"","expandable":false,"children":[]},{"name":"thumbnail","type":"`null` \\| `string`","description":"A URL string to a small image of the contents of the Line Item.","optional":false,"defaultValue":"","expandable":false,"children":[]},{"name":"is_return","type":"`boolean`","description":"Is the item being returned","optional":false,"defaultValue":"false","expandable":false,"children":[]},{"name":"is_giftcard","type":"`boolean`","description":"Flag to indicate if the Line Item is a Gift Card.","optional":false,"defaultValue":"false","expandable":false,"children":[]},{"name":"should_merge","type":"`boolean`","description":"Flag to indicate if new Line Items with the same variant should be merged or added as an additional Line Item.","optional":false,"defaultValue":"true","expandable":false,"children":[]},{"name":"allow_discounts","type":"`boolean`","description":"Flag to indicate if the Line Item should be included when doing discount calculations.","optional":false,"defaultValue":"true","expandable":false,"children":[]},{"name":"has_shipping","type":"`null` \\| `boolean`","description":"Flag to indicate if the Line Item has fulfillment associated with it.","optional":false,"defaultValue":"","expandable":false,"children":[]},{"name":"unit_price","type":"`number`","description":"The price of one unit of the content in the Line Item. This should be in the currency defined by the Cart/Order/Swap/Claim that the Line Item belongs to.","optional":false,"defaultValue":"","expandable":false,"children":[]},{"name":"variant_id","type":"`null` \\| `string`","description":"The id of the Product Variant contained in the Line Item.","optional":false,"defaultValue":"","expandable":false,"children":[]},{"name":"variant","type":"[ProductVariant](../../entities/classes/entities.ProductVariant.mdx)","description":"The details of the product variant that this item was created from.","optional":false,"defaultValue":"","expandable":true,"children":[]},{"name":"product_id","type":"`null` \\| `string`","description":"","optional":false,"defaultValue":"","expandable":false,"children":[]},{"name":"quantity","type":"`number`","description":"The quantity of the content in the Line Item.","optional":false,"defaultValue":"","expandable":false,"children":[]},{"name":"fulfilled_quantity","type":"`null` \\| `number`","description":"The quantity of the Line Item that has been fulfilled.","optional":false,"defaultValue":"","expandable":false,"children":[]},{"name":"returned_quantity","type":"`null` \\| `number`","description":"The quantity of the Line Item that has been returned.","optional":false,"defaultValue":"","expandable":false,"children":[]},{"name":"shipped_quantity","type":"`null` \\| `number`","description":"The quantity of the Line Item that has been shipped.","optional":false,"defaultValue":"","expandable":false,"children":[]},{"name":"metadata","type":"`Record<string, unknown>`","description":"An optional key-value map with additional details","optional":false,"defaultValue":"","expandable":false,"children":[]},{"name":"includes_tax","type":"`boolean`","description":"Indicates if the line item unit\\_price include tax","optional":false,"defaultValue":"false","expandable":false,"featureFlag":"tax_inclusive_pricing","children":[]},{"name":"original_item_id","type":"`null` \\| `string`","description":"The ID of the original line item. This is useful if the line item belongs to a resource that references an order, such as a return or an order edit.","optional":true,"defaultValue":"","expandable":false,"children":[]},{"name":"order_edit_id","type":"`null` \\| `string`","description":"The ID of the order edit that the item may belong to.","optional":true,"defaultValue":"","expandable":false,"children":[]},{"name":"order_edit","type":"`null` \\| [OrderEdit](../../entities/classes/entities.OrderEdit.mdx)","description":"The details of the order edit.","optional":true,"defaultValue":"","expandable":true,"children":[]},{"name":"refundable","type":"`null` \\| `number`","description":"The amount that can be refunded from the given Line Item. Takes taxes and discounts into consideration.","optional":true,"defaultValue":"","expandable":false,"children":[]},{"name":"subtotal","type":"`null` \\| `number`","description":"The subtotal of the line item","optional":true,"defaultValue":"","expandable":false,"children":[]},{"name":"tax_total","type":"`null` \\| `number`","description":"The total of tax of the line item","optional":true,"defaultValue":"","expandable":false,"children":[]},{"name":"total","type":"`null` \\| `number`","description":"The total amount of the line item","optional":true,"defaultValue":"","expandable":false,"children":[]},{"name":"original_total","type":"`null` \\| `number`","description":"The original total amount of the line item","optional":true,"defaultValue":"","expandable":false,"children":[]},{"name":"original_tax_total","type":"`null` \\| `number`","description":"The original tax total amount of the line item","optional":true,"defaultValue":"","expandable":false,"children":[]},{"name":"discount_total","type":"`null` \\| `number`","description":"The total of discount of the line item rounded","optional":true,"defaultValue":"","expandable":false,"children":[]},{"name":"raw_discount_total","type":"`null` \\| `number`","description":"The total of discount of the line item","optional":true,"defaultValue":"","expandable":false,"children":[]},{"name":"gift_card_total","type":"`null` \\| `number`","description":"The total of the gift card of the line item","optional":true,"defaultValue":"","expandable":false,"children":[]}]},{"name":"taxLines","type":"([LineItemTaxLine](../../entities/classes/entities.LineItemTaxLine.mdx) \\| [ShippingMethodTaxLine](../../entities/classes/entities.ShippingMethodTaxLine.mdx))[]","description":"The tax lines used for the calculation","optional":false,"defaultValue":"","expandable":false,"children":[]},{"name":"calculationContext","type":"[TaxCalculationContext](../types/medusa.TaxCalculationContext.mdx)","description":"Other details relevant for the calculation","optional":false,"defaultValue":"","expandable":false,"children":[{"name":"shipping_address","type":"[Address](../../entities/classes/entities.Address.mdx) \\| `null`","description":"The shipping address used in the cart.","optional":false,"defaultValue":"","expandable":false,"children":[]},{"name":"customer","type":"[Customer](../../entities/classes/entities.Customer.mdx)","description":"The customer that the cart belongs to.","optional":false,"defaultValue":"","expandable":false,"children":[]},{"name":"region","type":"[Region](../../entities/classes/entities.Region.mdx)","description":"The cart's region.","optional":false,"defaultValue":"","expandable":false,"children":[]},{"name":"is_return","type":"`boolean`","description":"Whether the cart is used in a return flow.","optional":false,"defaultValue":"","expandable":false,"children":[]},{"name":"shipping_methods","type":"[ShippingMethod](../../entities/classes/entities.ShippingMethod.mdx)[]","description":"The shipping methods used in the cart.","optional":false,"defaultValue":"","expandable":false,"children":[]},{"name":"allocation_map","type":"[LineAllocationsMap](../types/medusa.LineAllocationsMap.mdx)","description":"The gift cards and discounts applied on line items.\nEach object key or property is an ID of a line item","optional":false,"defaultValue":"","expandable":false,"children":[]}]}]} expandUrl="https://docs.medusajs.com/development/entities/repositories#retrieving-a-list-of-records" sectionTitle="calculate"/>

#### Returns

<ParameterTypes parameters={[{"name":"Promise","type":"Promise&#60;number&#62;","optional":false,"defaultValue":"","description":"The calculated tax total","expandable":false,"children":[{"name":"number","type":"`number`","optional":false,"defaultValue":"","description":"","expandable":false,"children":[]}]}]} expandUrl="https://docs.medusajs.com/development/entities/repositories#retrieving-a-list-of-records" sectionTitle="calculate"/>

### withTransaction

#### Parameters

<ParameterTypes parameters={[{"name":"transactionManager","type":"`EntityManager`","description":"","optional":true,"defaultValue":"","expandable":false,"children":[]}]} expandUrl="https://docs.medusajs.com/development/entities/repositories#retrieving-a-list-of-records" sectionTitle="withTransaction"/>

#### Returns

<ParameterTypes parameters={[{"name":"this","type":"`this`","optional":false,"defaultValue":"","description":"","expandable":false,"children":[]}]} expandUrl="https://docs.medusajs.com/development/entities/repositories#retrieving-a-list-of-records" sectionTitle="withTransaction"/>

### shouldRetryTransaction\_

#### Parameters

<ParameterTypes parameters={[{"name":"err","type":"`Record<string, unknown>` \\| `object`","description":"","optional":false,"defaultValue":"","expandable":false,"children":[]}]} expandUrl="https://docs.medusajs.com/development/entities/repositories#retrieving-a-list-of-records" sectionTitle="shouldRetryTransaction_"/>

#### Returns

<ParameterTypes parameters={[{"name":"boolean","type":"`boolean`","optional":false,"defaultValue":"","description":"","expandable":false,"children":[]}]} expandUrl="https://docs.medusajs.com/development/entities/repositories#retrieving-a-list-of-records" sectionTitle="shouldRetryTransaction_"/>

### atomicPhase\_

Wraps some work within a transactional block. If the service already has
a transaction manager attached this will be reused, otherwise a new
transaction manager is created.

#### Type Parameters

<ParameterTypes parameters={[{"name":"TResult","type":"`object`","description":"","optional":false,"defaultValue":"","expandable":false,"children":[]},{"name":"TError","type":"`object`","description":"","optional":false,"defaultValue":"","expandable":false,"children":[]}]} expandUrl="https://docs.medusajs.com/development/entities/repositories#retrieving-a-list-of-records" sectionTitle="atomicPhase_"/>

#### Parameters

<ParameterTypes parameters={[{"name":"work","type":"(`transactionManager`: `EntityManager`) => Promise&#60;TResult&#62;","description":"the transactional work to be done","optional":false,"defaultValue":"","expandable":false,"children":[]},{"name":"isolationOrErrorHandler","type":"`IsolationLevel` \\| (`error`: TError) => Promise&#60;void \\| TResult&#62;","description":"the isolation level to be used for the work.","optional":true,"defaultValue":"","expandable":false,"children":[]},{"name":"maybeErrorHandlerOrDontFail","type":"(`error`: TError) => Promise&#60;void \\| TResult&#62;","description":"Potential error handler","optional":true,"defaultValue":"","expandable":false,"children":[]}]} expandUrl="https://docs.medusajs.com/development/entities/repositories#retrieving-a-list-of-records" sectionTitle="atomicPhase_"/>

#### Returns

<ParameterTypes parameters={[{"name":"Promise","type":"Promise&#60;TResult&#62;","optional":false,"defaultValue":"","description":"the result of the transactional work","expandable":false,"children":[{"name":"TResult","type":"TResult","optional":false,"defaultValue":"","description":"","expandable":false,"children":[]}]}]} expandUrl="https://docs.medusajs.com/development/entities/repositories#retrieving-a-list-of-records" sectionTitle="atomicPhase_"/>