> ## Documentation Index > Fetch the complete documentation index at: https://docs.withflex.com/llms.txt > Use this file to discover all available pages before exploring further. # Get Refund Preview > Previews the prorated refund that would result from canceling a subscription. Runs the same validation as a real prorated refund but issues no refund and creates no records, so it is safe to call repeatedly. Returns the prorated amount available to refund, the amount paid on the latest invoice, the current billing period, and the card that would be refunded. ## OpenAPI ````yaml /openapi.json get /v1/subscriptions/{id}/refund_preview openapi: 3.1.0 info: title: Flex API description: >- The Flex API powers HSA/FSA payment processing for healthcare commerce: checkout sessions, payment intents, subscriptions, customers, refunds, disputes, and eligibility. Authenticate with your partner API key as a Bearer token. All endpoints are scoped to your partner account, and test mode is fully supported via test API keys. version: 0.1.0 servers: - url: https://api.withflex.com security: - BearerAuth: [] tags: - name: Balance Transactions - name: Captures - name: Checkout Sessions - name: Coupons - name: Customers - name: Disputes - name: Events - name: Exports - name: Files - name: Invoices - name: Letters - name: Orders - name: Payment Intents - name: Payment Links - name: Payouts - name: Prices - name: Products - name: Promo Codes - name: Receipts - name: Refunds - name: Setup Intents - name: Shipping Rates - name: Subscriptions paths: /v1/subscriptions/{id}/refund_preview: get: tags: - Subscriptions summary: Get Refund Preview description: >- Previews the prorated refund that would result from canceling a subscription. Runs the same validation as a real prorated refund but issues no refund and creates no records, so it is safe to call repeatedly. Returns the prorated amount available to refund, the amount paid on the latest invoice, the current billing period, and the card that would be refunded. operationId: v1.subscriptions.refund_preview parameters: - in: path name: id required: true schema: examples: - fsub_01J9XR8M3K7VZ8N2YB4WJ6T0RA type: string style: simple example: fsub_01J9XR8M3K7VZ8N2YB4WJ6T0RA responses: '200': description: Success content: application/json: schema: $ref: '#/components/schemas/RefundPreviewResponse' example: prorated_amount_available_to_refund: 2500 invoice_amount_paid: 2500 current_period_start: '2026-06-15T14:30:00Z' current_period_end: '2026-06-15T14:30:00Z' payment_method_id: fpm_01J9XR8M3K7VZ8N2YB4WJ6T0RA last4: '4242' '401': description: Unauthorized content: application/json: schema: $ref: '#/components/schemas/HttpErrorOut' example: code: string detail: string '403': description: Forbidden content: application/json: schema: $ref: '#/components/schemas/HttpErrorOut' example: code: string detail: string '404': description: Not Found content: application/json: schema: $ref: '#/components/schemas/HttpErrorOut' example: code: string detail: string '409': description: Conflict content: application/json: schema: $ref: '#/components/schemas/HttpErrorOut' example: code: string detail: string '422': description: Validation Error content: application/json: schema: $ref: '#/components/schemas/HTTPValidationError' example: detail: - loc: - string msg: string type: string '429': description: Too Many Requests content: application/json: schema: $ref: '#/components/schemas/HttpErrorOut' example: code: string detail: string components: schemas: RefundPreviewResponse: description: >- The result of previewing a prorated refund for a subscription cancellation, without issuing any refund. Reflects what would be refunded based on the remaining billing period. type: object required: - current_period_end - current_period_start - invoice_amount_paid - prorated_amount_available_to_refund properties: prorated_amount_available_to_refund: description: >- Prorated amount available to refund, in the smallest currency unit (e.g., `1499` = $14.99 USD), based on the unused portion of the current billing period. type: integer format: int64 example: 2500 invoice_amount_paid: description: >- Total amount paid on the subscription's latest invoice, in the smallest currency unit (e.g., `2999` = $29.99 USD). type: integer format: int64 example: 2500 current_period_start: $ref: '#/components/schemas/Timestamptz' description: Start of the current billing period, as an RFC 3339 timestamp. example: '2026-06-15T14:30:00Z' current_period_end: $ref: '#/components/schemas/Timestamptz' description: End of the current billing period, as an RFC 3339 timestamp. example: '2026-06-15T14:30:00Z' payment_method_id: description: The payment method ID that would be refunded, if available type: - string - 'null' example: fpm_01J9XR8M3K7VZ8N2YB4WJ6T0RA last4: description: Last 4 digits of the card that would be refunded, if available type: - string - 'null' example: '4242' example: prorated_amount_available_to_refund: 2500 invoice_amount_paid: 2500 current_period_start: '2026-06-15T14:30:00Z' current_period_end: '2026-06-15T14:30:00Z' payment_method_id: fpm_01J9XR8M3K7VZ8N2YB4WJ6T0RA last4: '4242' HttpErrorOut: title: HttpError description: The error response returned when a request cannot be completed. type: object required: - code - detail properties: code: description: A short machine-readable error code identifying the type of error. type: string detail: description: A human-readable explanation of what went wrong. type: string example: code: string detail: string HTTPValidationError: description: The error response returned when request validation fails (HTTP 422). type: object required: - detail properties: detail: description: The list of validation errors, one entry per invalid field. type: array items: $ref: '#/components/schemas/ValidationErrorItem' example: detail: - loc: - string msg: string type: string Timestamptz: description: >- A timestamp encoded as an RFC 3339 / ISO 8601 string (e.g. `2026-06-15T14:30:00Z`). type: string example: string ValidationErrorItem: description: >- Validation errors have their own schema to provide context for invalid requests eg. mismatched types and out of bounds values. There may be any number of these per 422 UNPROCESSABLE ENTITY error. type: object required: - loc - msg - type properties: loc: description: >- The location as a [`Vec`] of [`String`]s -- often in the form `["body", "field_name"]`, `["query", "field_name"]`, etc. They may, however, be arbitarily deep. type: array items: type: string msg: description: The message accompanying the validation error item. type: string type: description: >- The type of error, often "type_error" or "value_error", but sometimes with more context like as "value_error.number.not_ge" type: string example: loc: - string msg: string type: string securitySchemes: BearerAuth: type: http scheme: bearer bearerFormat: API Key description: Use a Bearer token to access this API. ````