> ## Documentation Index > Fetch the complete documentation index at: https://developer.fabric.inc/llms.txt > Use this file to discover all available pages before exploring further. # Update fee > Updates a fee in the cart. The Cart ID from the [Create cart](/v3/cart-and-checkout/api-reference/carts-v3/carts/carts) endpoint is used in the path parameter. The Fee ID from the [Create fee](/v3/cart-and-checkout/api-reference/carts-v3/fees/delete-fees) endpoint is used in the path parameter. ## OpenAPI ````yaml modular-cart patch /carts/{cartId}/fees/{feeId} openapi: 3.0.1 info: title: Cart API description: >- fabric's **Cart API** lets you add, update, and remove items from your Storefront cart, either as a guest user or as a logged-in user. It also provides functionality to merge carts when you switch from guest user to logged-in user, and apply coupons and other attributes (for example, gift wrapping) to the line items. Additionally, the API supports more advanced tasks such as using multiple carts within a B2B organization, sharing carts, and supporting a unified cart experience for multi-region and multi-brand businesses.

The Cart API provides high performance, scalability, multi-tenancy, and configurability to the end-to-end order processing actions that start from the item being added to the cart; through the pre-checkout stage that includes billing, shipping, and payment details; to the checkout stage where the order is processed and confirmed by fabric's Order Management System (OMS) contact: name: Cart Support email: support.cnc@fabric.inc license: name: fabric API License url: https://fabric.inc/api-license version: 3.0.0 servers: - url: https://api.fabric.inc/v3 security: - bearerAuth: [] tags: - name: Cart description: >- Cart endpoints are used to do basic cart operations, such as create a cart, add item to the corresponding cart, update items, remove items, delete cart, update status of the cart, and more. - name: Items description: Item endpoints are used to add, update and remove items from the Cart. - name: Cart Fees description: >- Cart fee endpoints are used to add, update and remove fees at the Cart level. - name: Fulfillment Fees description: >- Fulfillment fees endpoints are used to add, update and remove fees at the Fulfillment level. - name: Addresses description: >- Address endpoints are used to add add, update and remove addresses from the Cart. - name: Item Fees description: >- Item fee endpoints are used to add, update and remove fees at the Item level. - name: Cart Adjustments description: >- Cart adjustment endpoints are used to add, update and remove adjustments at the Cart level. - name: Payments description: >- Payments endpoints are used to add add, update and remove payments from the Cart. - name: Customer description: >- Customer endpoints are used do basic customer operations, such as update a customer, add attributes and more. - name: Coupons description: Coupon endpoints are used to add and remove coupons from the Cart - name: Item Adjustments description: >- Item adjustments endpoints are used to add, update and remove adjustments at the Item level. - name: Fulfillment Adjustments description: >- Fulfillment adjustments endpoints are used to add, update and remove adjustments at the Fulfillment level. - name: Fulfillments description: >- Fulfillment endpoints are used to add add, update and remove fulfillments from the Cart. - name: Validations description: >- Validation endpoints are used to pass in data from fabric and third-party services to perform business logic on the Cart paths: /carts/{cartId}/fees/{feeId}: patch: tags: - Cart Fees summary: Update fee description: > Updates a fee in the cart. The Cart ID from the [Create cart](/v3/cart-and-checkout/api-reference/carts-v3/carts/carts) endpoint is used in the path parameter. The Fee ID from the [Create fee](/v3/cart-and-checkout/api-reference/carts-v3/fees/delete-fees) endpoint is used in the path parameter. operationId: updateFee_1 parameters: - name: cartId in: path required: true schema: type: string description: >- The 24-character system-generated Cart ID. This ID is generated using the [Create cart](/v3/cart-and-checkout/api-reference/carts-v3/carts/carts) endpoint. - name: feeId in: path required: true schema: type: string description: >- The Fee ID generated from the [Create fee](/v3/cart-and-checkout/api-reference/carts-v3/fees/create-fees) endpoint. - name: x-fabric-tenant-id in: header description: > A header used by fabric to identify the tenant making the request. You must include tenant id in the authentication header for an API request to access any of fabric’s endpoints. You can retrieve the tenant id , which is also called account id, from [Copilot](/v3/platform/settings/account-details/getting-the-account-id). This header is required. required: true schema: type: string example: 617329dfd5288b0011332311 - name: x-fabric-request-id in: header description: ' Unique request ID for tracking.' required: false schema: type: string example: 263e731c-45c8-11ed-b878-0242ac120002 - name: x-fabric-channel-id in: header description: >- x-fabric-channel-id identifies the sales channel through which the API request is being made; primarily for multichannel use cases. It is a required field. The default US channel is 12 while the default Canada channel is 11. required: false schema: type: string example: '12' requestBody: content: application/json: schema: $ref: '#/components/schemas/UpdateFeeRequestWithTaxDetails' required: true responses: '200': description: OK content: application/json: schema: $ref: '#/components/schemas/UpdatedFee' '400': description: Client error content: application/json: schema: $ref: '#/components/schemas/ClientError' '404': description: Cart or Item not found content: application/json: schema: $ref: '#/components/schemas/NotFound' components: schemas: UpdateFeeRequestWithTaxDetails: type: object properties: name: type: string description: Name of the fee example: Eco Fee price: $ref: '#/components/schemas/ResourcePrice' taxable: type: boolean description: A boolean value that determines whether a fee is taxable. example: true attributes: type: object additionalProperties: type: object description: Custom attributes example: source: eco description: Custom attributes example: source: eco taxDetails: $ref: '#/components/schemas/FeeTaxDetailsRequest' description: Fee Request UpdatedFee: type: object properties: id: type: string description: >- The Fee ID generated from the [Create fee](/v3/cart-and-checkout/api-reference/carts-v3/fees/create-fees) endpoint. example: a8577d7f-0d4d-4b22-8e85-7b4a2e90dc93 name: type: string description: Name of the fee example: Eco Fee price: $ref: '#/components/schemas/ResourcePrice' taxable: type: boolean description: A boolean value that determines whether a fee is taxable. example: true attributes: type: object additionalProperties: type: object description: Custom attributes used to describe a fee, such as an eco fee. example: source: eco description: Custom attributes used to describe a fee, such as an eco fee. example: source: eco tax: $ref: '#/components/schemas/TaxCollection' updatedAt: type: string description: The date and time when the fee was last updated. example: '2024-06-13T16:50:00.682Z' createdAt: type: string description: The date and time when the fee was created. example: '2024-06-13T16:50:00.682Z' taxDetails: $ref: '#/components/schemas/FeeTaxDetails' description: Fee ClientError: type: object properties: type: type: string description: Error code, meant for machine consumption example: BAD_REQUEST message: type: string description: Human-readable error description example: x-fabric-tenant-id is required description: Client error details NotFound: type: object properties: type: type: string description: Error code, meant for machine consumption example: CART_NOT_FOUND message: type: string description: Human-readable error description example: Cart not found description: Resource Not Found ResourcePrice: required: - amount type: object properties: amount: minimum: 0 exclusiveMinimum: false type: number description: Total fees amount example: 12.99 description: Price details FeeTaxDetailsRequest: type: object properties: destinationAddress: type: string description: Identifier of the address example: c86f777b-1885-4ddf-961d-542ba80a69b8 originAddress: type: string description: Identifier of the address example: c86f777b-1885-4ddf-961d-542ba80a69b8 description: Tax details used to determine tax for a cart fee TaxCollection: type: object properties: total: type: number description: Tax total in the collection. example: 3 collection: type: array description: An array containing taxes in a collection. items: $ref: '#/components/schemas/Tax' description: A collection of taxes. FeeTaxDetails: type: object properties: destinationAddress: type: string description: The destination address where the item will be delivered. example: c86f777b-1885-4ddf-961d-542ba80a69b8 originAddress: type: string description: The origin address from which the item will be fulfilled. example: c86f777b-1885-4ddf-961d-542ba80a69b8 description: Tax details used to determine tax for a cart fee. Tax: type: object properties: amount: type: number description: Tax amount example: 3 attributes: type: object additionalProperties: type: object description: >- Custom attributes to provide more context to the tax, such as the rate and the type of tax. example: rate: '5.0' type: COUNTY description: >- Custom attributes to provide more context to the tax, such as the rate and the type of tax. example: rate: '5.0' type: COUNTY description: Tax securitySchemes: bearerAuth: type: http scheme: bearer bearerFormat: JWT description: > This is the authorization token used to authenticate the request. You must pass the access token generated from the system app. For more information, see the [Making your first API request](/v3/api-reference/getting-started/getting-started-with-fabric-apis#procedure) section. ````