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Adjust balance POSTApply an Offer to a subscription PUTCancel subscription POSTChange plan POSTCreate a recovery payment link for a past due subscription POSTCreate subscription POSTGet active subscription GETGet subscription by ID GETList subscriptions GETPause subscription POSTPreview plan change POSTReactivate a past due or canceled subscription POSTRemove an Offer from a pending checkout DELETEResume subscription POSTRevoke scheduled pause DELETETop up balance POSTRevert scheduled cancellation POSTUpdate payment method POSTUpdate subscription pause PATCH
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Preview plan change

Preview proration details for an immediate plan change without applying it. Free-to-paid changes are never scheduled and the change-plan endpoint always returns hosted checkout for them. For paid plans, interval direction takes precedence: a longer interval is immediate and a shorter interval is scheduled. When the interval is unchanged, a higher-sort-order plan is immediate and a lower-sort-order plan is scheduled. A paid-to-free change is always scheduled. Returns credit, charge, and net amount. The target plan must belong to the same plan group as the current plan, otherwise a 400 with code `plans_not_in_same_group` is returned. A change between two free plans has nothing to prorate and returns a zero-amount estimate. Scheduled changes return a 400 with code `plan_change_scheduled`; apply those via the change-plan endpoint. Pass offerId to quote the destination plan with an Offer.

POST
/subscriptions/{id}/preview-change

Preview proration details for an immediate plan change without applying it. Free-to-paid changes are never scheduled and the change-plan endpoint always returns hosted checkout for them. For paid plans, interval direction takes precedence: a longer interval is immediate and a shorter interval is scheduled. When the interval is unchanged, a higher-sort-order plan is immediate and a lower-sort-order plan is scheduled. A paid-to-free change is always scheduled. Returns credit, charge, and net amount. The target plan must belong to the same plan group as the current plan, otherwise a 400 with code plans_not_in_same_group is returned. A change between two free plans has nothing to prorate and returns a zero-amount estimate. Scheduled changes return a 400 with code plan_change_scheduled; apply those via the change-plan endpoint. Pass offerId to quote the destination plan with an Offer.

Authorization

ApiKeyAuth
x-api-key<token>

In: header

Path Parameters

id*string

Header Parameters

Idempotency-Key?string

Unique key used to safely retry this write for 24 hours without applying it twice.

Length1 <= length <= 200

Request Body

application/json

TypeScript Definitions

Use the request body type in TypeScript.

Response Body

application/json

application/json

application/json

application/json

application/json

application/json

application/json

application/json

application/json

curl -X POST "https://example.com/subscriptions/string/preview-change" \  -H "Content-Type: application/json" \  -d '{    "planId": "string"  }'
{  "currency": "usd",  "currentPlanCredit": 2000,  "newPlanCharge": 4000,  "estimatedTotal": 2000,  "effectiveDate": "2026-09-07T12:00:00.000Z",  "daysRemaining": 30,  "totalDays": 30,  "isUpgrade": true,  "object": "plan_change_preview",  "livemode": false}
{  "error": {    "type": "validation_error",    "code": "validation_error",    "message": "The request contains an invalid parameter.",    "doc_url": "https://commet.co/docs/api-reference/2026-08-27/errors/validation_error.md"  }}
{  "error": {    "type": "authentication_error",    "code": "unauthorized",    "message": "A valid API key is required.",    "doc_url": "https://commet.co/docs/api-reference/2026-08-27/errors/unauthorized.md"  }}
{  "error": {    "type": "authentication_error",    "code": "forbidden",    "message": "You do not have permission to perform this operation.",    "doc_url": "https://commet.co/docs/api-reference/2026-08-27/errors/forbidden.md"  }}
{  "error": {    "type": "not_found_error",    "code": "not_found",    "message": "The requested resource was not found.",    "doc_url": "https://commet.co/docs/api-reference/2026-08-27/errors/not_found.md"  }}
{  "error": {    "type": "conflict_error",    "code": "idempotency_in_progress",    "message": "A request with this idempotency key is still being processed.",    "doc_url": "https://commet.co/docs/api-reference/2026-08-27/errors/idempotency_in_progress.md"  }}
{  "error": {    "type": "rate_limit_error",    "code": "rate_limited",    "message": "Too many requests. Retry after the interval specified in the Retry-After header.",    "doc_url": "https://commet.co/docs/api-reference/2026-08-27/errors/rate_limited.md"  }}
{  "error": {    "type": "internal_error",    "code": "internal_error",    "message": "An unexpected error occurred while processing the request.",    "doc_url": "https://commet.co/docs/api-reference/2026-08-27/errors/internal_error.md"  }}
{  "error": {    "type": "internal_error",    "code": "idempotency_unavailable",    "message": "Idempotency storage is temporarily unavailable. Retry with the same idempotency key.",    "doc_url": "https://commet.co/docs/api-reference/2026-08-27/errors/idempotency_unavailable.md"  }}

Pause subscription POST

Pause immediately or schedule a pause for the end of the current billing or trial period. Set durationDays to null for an indefinite pause.

Reactivate a past due or canceled subscription POST

Reactivates a subscription. A past_due subscription retries its outstanding renewal charge (recovering to active on success). A canceled subscription generates a fresh invoice, charges the saved card, and resets the billing period. On a successful charge the subscription becomes active; a declined charge returns an error with a recoveryUrl in the error details that can be sent to the customer to update their card. A canceled subscription may apply an Offer by offerId; past-due recovery cannot.

planId*string
Length1 <= length
billingInterval?string

Value in

  • "weekly"
  • "monthly"
  • "quarterly"
  • "yearly"
  • "one_time"
offerId?string
Length1 <= length