> ## Documentation Index > Fetch the complete documentation index at: https://docs.kalshi.com/llms.txt > Use this file to discover all available pages before exploring further. # Amend Order > Endpoint for amending the price and/or max number of fillable contracts in an existing margin order. Amending a resting order preserves queue position only when the amendment decreases size. All other amendments — like increasing size or changing price forfeit queue position and place the order at the back of the queue. ## OpenAPI ````yaml /perps_openapi.yaml post /margin/orders/{order_id}/amend openapi: 3.0.0 info: title: Kalshi Trade API Manual Endpoints version: 0.0.1 description: >- Manually defined OpenAPI spec for endpoints being migrated to spec-first approach servers: - url: https://external-api.kalshi.com/trade-api/v2 description: Production perps REST API server - url: https://external-api.demo.kalshi.co/trade-api/v2 description: Demo perps REST API server security: [] tags: - name: account description: Account information endpoints - name: exchange description: Exchange status and information endpoints - name: market description: Market data endpoints - name: orders description: Order management endpoints - name: order-groups description: Order group management endpoints - name: portfolio description: Portfolio and balance information endpoints - name: fcm description: FCM member specific endpoints - name: risk description: Margin risk metrics, parameters, and limits - name: funding description: Funding rates and payment history - name: fees description: Margin fee schedule paths: /margin/orders/{order_id}/amend: post: tags: - orders summary: Amend Order description: >- Endpoint for amending the price and/or max number of fillable contracts in an existing margin order. operationId: AmendMarginOrder parameters: - $ref: '#/components/parameters/OrderIdPath' - $ref: '#/components/parameters/SubaccountQueryDefaultPrimary' requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/AmendMarginOrderRequest' responses: '200': description: Order amended successfully content: application/json: schema: $ref: '#/components/schemas/AmendMarginOrderResponse' '400': $ref: '#/components/responses/BadRequestError' '401': $ref: '#/components/responses/UnauthorizedError' '404': $ref: '#/components/responses/NotFoundError' '500': $ref: '#/components/responses/InternalServerError' security: - kalshiAccessKey: [] kalshiAccessSignature: [] kalshiAccessTimestamp: [] components: parameters: OrderIdPath: name: order_id in: path required: true description: Order ID schema: type: string SubaccountQueryDefaultPrimary: name: subaccount in: query required: false description: Subaccount number (0 for primary, 1-63 for subaccounts). Defaults to 0. schema: type: integer minimum: 0 default: 0 schemas: AmendMarginOrderRequest: type: object required: - ticker - side - price - count properties: ticker: type: string description: Market ticker x-oapi-codegen-extra-tags: validate: required,min=1 side: $ref: '#/components/schemas/BookSide' description: Side of the order x-oapi-codegen-extra-tags: validate: required,oneof=bid ask price: $ref: '#/components/schemas/FixedPointDollars' description: Updated price for the order in fixed-point dollars. x-go-type-skip-optional-pointer: true count: $ref: '#/components/schemas/FixedPointCount' description: String representation of the updated quantity for the order. x-go-type-skip-optional-pointer: true client_order_id: type: string description: The original client-specified order ID to be amended x-go-type-skip-optional-pointer: true updated_client_order_id: type: string description: The new client-specified order ID after amendment x-go-type-skip-optional-pointer: true AmendMarginOrderResponse: type: object required: - order_id properties: order_id: type: string client_order_id: type: string remaining_count: $ref: '#/components/schemas/FixedPointCount' nullable: true x-omitempty: false description: >- Number of contracts remaining after the amend. Only present when the amend caused a fill or changed the resting size. fill_count: $ref: '#/components/schemas/FixedPointCount' nullable: true x-omitempty: false description: >- Number of contracts filled as a result of the amend crossing the book. Only present when fills occurred or remaining size changed. average_fill_price: $ref: '#/components/schemas/FixedPointDollars' nullable: true x-omitempty: false description: >- Volume-weighted average fill price for fills resulting from the amend. Only present when fills occurred. average_fee_paid: $ref: '#/components/schemas/FixedPointDollars' nullable: true x-omitempty: false description: >- Volume-weighted average fee paid per contract for fills resulting from the amend. Only present when fills occurred. BookSide: type: string enum: - bid - ask description: The side of an order or trade (bid or ask) FixedPointDollars: type: string description: >- US dollar amount as a fixed-point decimal string with up to 6 decimal places of precision. This is the maximum supported precision; valid quote intervals for a given market are constrained by that market's price level structure. example: '0.5600' FixedPointCount: type: string description: >- Fixed-point contract count string (2 decimals, e.g., "10.00"; referred to as "fp" in field names). Requests accept 0-2 decimal places (e.g., "10", "10.0", "10.00"); responses always emit 2 decimals. Fractional contract values (e.g., "2.50") are supported; the minimum granularity is 0.01 contracts. example: '10.00' ErrorResponse: type: object properties: code: type: string description: Error code message: type: string description: Human-readable error message details: type: string description: Additional details about the error, if available service: type: string description: The name of the service that generated the error responses: BadRequestError: description: Bad request - invalid input content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' UnauthorizedError: description: Unauthorized - authentication required content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' NotFoundError: description: Resource not found content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' InternalServerError: description: Internal server error content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' securitySchemes: kalshiAccessKey: type: apiKey in: header name: KALSHI-ACCESS-KEY description: Your API key ID kalshiAccessSignature: type: apiKey in: header name: KALSHI-ACCESS-SIGNATURE description: RSA-PSS signature of the request kalshiAccessTimestamp: type: apiKey in: header name: KALSHI-ACCESS-TIMESTAMP description: Request timestamp in milliseconds ````