Payload

All webhook payloads follow a consistent top-level structure with event-specific data nested within the data object.

subscriptionIdstring

The subscription ID.

customerIdstring

The customer ID. Returns your externalId if you provided one when creating the customer, otherwise returns the Commet publicId.

externalIdstring

Your external ID for this customer. Only included if you set an externalId when creating the customer.

previousPlanobject

The previous plan (id and name).

currentPlanobject

The new plan (id and name).

billingIntervalstring | null

The billing interval (monthly, yearly).

creditnumber | null

Prorated credit in cents from the previous plan.

chargenumber | null

Prorated charge in cents for the new plan.

totalChargednumber | null

Total amount charged in cents.

{
  "event": "subscription.plan_changed",
  "timestamp": "2026-04-15T12:00:00.000Z",
  "organizationId": "org_abc123",
  "data": {
    "subscriptionId": "sub_1a2b3c4d",
    "customerId": "user_123",
    "externalId": "user_123",
    "previousPlan": {
      "id": "plan_starter",
      "name": "Starter"
    },
    "currentPlan": {
      "id": "plan_pro",
      "name": "Pro"
    },
    "billingInterval": "monthly",
    "credit": 1500,
    "charge": 4900,
    "totalCharged": 3400
  }
}