# Updating an existing Billing Milestone

Edit information for a billing milestone in your Billing Schedule. You can only edit billing milestones that have not been invoiced.
This endpoint returns structured Billing Milestones objects.
As with all Kantata OX API endpoints, the returned data will be referenced in sorted order in the `results` array
and will be indexed by ID in the `billing_milestones` top-level JSON key.
Please see our [Response Format](#section/Response-Format) section for more information.

Endpoint: PUT /billing_milestones/{id}
Version: 1.0.0

## Path parameters:

  - `id` (integer, required)
    The ID of the Model.

## Query parameters:

  - `include` (string)
    Any of the below associations can be included in your request by providing the `include` param, e.g. `include=association1,association2`.
- `external_references` (ExternalReference) - Includes references to external integrations for this object.
- `invoices` (Invoice) - Retrieves the invoices that the billing milestones are on. The response will include `invoice_ids`, which references the data in the `invoices` top-level key.
- `story` (Story) - Retrieves the task associated with the billing milestone. The response will include `story_id`, which references the data in the `stories` top-level key.
- `workspace` (Workspace) - Retrieves the project that the billing milestone is in. The response will include `workspace_id`, which references the data in the `workspaces` top-level key.

## Request fields (application/json):

  - `billing_milestone` (object)

  - `billing_milestone.title` (string)
    The title of the billing milestone.

  - `billing_milestone.amount_in_cents` (integer)
    The billing milestone amount, in the subunits of the currency (e.g. cents for USD).

  - `billing_milestone.date_to_invoice` (string)
    The date that the billing milestone becomes invoiceable. The date must be in [ISO 8601](https://www.w3.org/TR/NOTE-datetime) format.

  - `billing_milestone.billing_type` (string)
    The billing type of the milestone. Can be 'fixed_date' or 'upon_completion'.

  - `billing_milestone.story_id` (integer)
    The ID of the story associated with the billing milestone. This field is required when the `billing_type` is set to `upon_completion`.

  - `billing_milestone.external_reference` (object)
    Typically populated programmatically by a third party system via an integration, this is an optional
object that holds data from an external system. It connects objects in an external system with objects in
Kantata OX (for example, to connect a Jira issue to a Kantata OX Project).

  - `billing_milestone.external_reference.service_name` (string, required)
    The provider name of the integration. If you are adding multiple external references to the same object, the `service_name` must be unique.

  - `billing_milestone.external_reference.service_model` (string, required)
    The object type of the external object this external reference belongs to.

  - `billing_milestone.external_reference.service_model_ref` (string, required)
    The object ID of the external object this external reference belongs to.

  - `billing_milestone.external_reference.status` (string)
    The status of the integration. Options are `successful`, `pending`,  or `failed`.

  - `billing_milestone.external_reference.external_message` (string)
    The message on the external object.

  - `billing_milestone.external_reference.external_link` (string)
    The link to the external object.

  - `billing_milestone.external_reference.external_status` (string)
    The status of the external object in the external system.

  - `billing_milestone.external_reference.locked` (boolean)
    Whether the subject is locked.

## Response 200 fields (application/json):

  - `count` (integer)

  - `meta` (object)

  - `meta.count` (integer)

  - `meta.page_count` (integer)

  - `meta.page_number` (integer)

  - `meta.page_size` (integer)

  - `results` (array)

  - `results.key` (string)

  - `results.id` (string)

## Response 400 fields (application/json):

  - `errors` (array)

  - `errors.type` (string)

  - `errors.message` (string)

## Response 401 fields (application/json):

  - `errors` (array)

  - `errors.type` (string)

  - `errors.message` (string)

## Response 403 fields (application/json):

  - `errors` (array)

  - `errors.type` (string)

  - `errors.message` (string)

## Response 404 fields (application/json):

  - `errors` (array)

  - `errors.type` (string)

  - `errors.message` (string)

## Response 422 fields (application/json):

  - `errors` (array)

  - `errors.type` (string)

  - `errors.message` (string)

## Response 503 fields (application/json):

  - `errors` (array)

  - `errors.type` (string)

  - `errors.message` (string)