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

# Change contract plan

> Switch a contract to a new plan effective from a given date (mid-term plan change). Requires `startDate` and `endDate`.

<Warning>**Not accessible by SystemUser role.** Requires Admin.</Warning>


## OpenAPI

````yaml put /contracts/{contractId}/plans/{contractPlanId}/change
openapi: 3.0.3
info:
  title: Enso API
  description: >-
    REST API for Enso's billing & metering platform. This reference covers
    endpoints accessible to the SystemUser role — the role used by API
    integrations.
  version: 1.0.0
  license:
    name: Proprietary
servers:
  - url: https://api.getenso.ai
    description: Production
security:
  - bearerAuth: []
tags:
  - name: Apps
    description: Third-party app integrations and credentials
  - name: Attributes
    description: Custom attribute definitions on catalog/customer entities
  - name: Auth
    description: Exchange API credentials for an access token
  - name: Billing
    description: Plans and plan items — what your contracts apply
  - name: Catalog
    description: SKUs and SKU groups — the product taxonomy that plans price against
  - name: Chatbot
    description: Conversational endpoints
  - name: Collections
    description: ''
  - name: Contracts
    description: Contracts that bind a customer to one or more billing plans
  - name: Customers
    description: Manage customer records — the parties Enso bills
  - name: Email templates
    description: Manage email templates
  - name: Entities
    description: Entities (legal entity, contracting organisation) used in billing
  - name: Events
    description: Raw event ingestion — the input to the metering pipeline
  - name: FSM (object lifecycle)
    description: >-
      Drive lifecycle transitions on Invoice/Contract/etc. — used for raise,
      send, mark-paid, etc.
  - name: FX Rates
    description: Currency conversion rates
  - name: Geography
    description: Country/state lookups — reference data for addresses
  - name: Invoices
    description: Invoice CRUD, items, sync, PDF generation, document upload
  - name: Jobs
    description: >-
      Background job orchestration — used by long-running operations like bulk
      sync
  - name: Masters
    description: ''
  - name: Meters
    description: Usage meters — the per-aggregation tally that feeds invoices
  - name: Objects
    description: Generic object schema and query — exposes the data model dynamically
  - name: Organisation
    description: ''
  - name: Organisation attributes
    description: Organisation-level custom attributes
  - name: Organisation settings
    description: Organisation-wide configuration values
  - name: Revenue
    description: Recognised revenue records derived from invoices
  - name: Usage
    description: Usage records — what got billed against each meter for a billing period
  - name: Users
    description: User account read access
paths:
  /contracts/{contractId}/plans/{contractPlanId}/change:
    put:
      tags:
        - Contracts
      summary: Change contract plan
      description: >-
        Switch a contract to a new plan effective from a given date (mid-term
        plan change). Requires `startDate` and `endDate`.
      operationId: changePlan
      parameters:
        - name: contractId
          in: path
          required: true
          description: Contract ID
          schema:
            type: string
        - name: contractPlanId
          in: path
          required: true
          description: Contract Plan ID
          schema:
            type: string
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              required:
                - startDate
                - endDate
              properties:
                startDate:
                  type: string
                  format: date
                  example: '2026-05-01'
                endDate:
                  type: string
                  format: date
                  example: '2027-04-30'
                PlanId:
                  type: string
                  example: '200'
      responses:
        '200':
          description: Success
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/SuccessEnvelope'
        '401':
          description: Unauthorized — token missing or invalid
        '403':
          description: Forbidden — insufficient policy permissions
        default:
          description: Client error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorEnvelope'
components:
  schemas:
    SuccessEnvelope:
      type: object
      properties:
        status:
          type: string
          example: success
        message:
          type: string
          example: Success
        data:
          description: Endpoint-specific payload (object, array, or null)
          type: object
          nullable: true
    ErrorEnvelope:
      type: object
      properties:
        status:
          type: string
          example: error
        message:
          type: string
          example: Forbidden
        errors:
          type: array
          items:
            type: object
  securitySchemes:
    bearerAuth:
      type: http
      scheme: bearer
      bearerFormat: JWT
      description: >-
        JWT bearer token obtained from POST /auth/system-login using your client
        credentials.

````