BillKit/Docs Console
Subscriptions

Preview update subscription

Quote what moving this subscription to another price would cost.

POST/v1/subscriptions/{subscription_id}/preview_update
Operation preview_update_subscription · Scope subscriptions:read · Spec snapshot 2026-09-13

Parameters

ParameterDescription
subscription_idstring · pathrequiredNo description in the spec.
target_price_idstringrequiredNo description in the spec.

Returns

Returns a PlanChangePreviewResponse object.

Errors

Status Cause
401 Missing or invalid API key.
403 Key is missing the subscriptions:read scope.
404 No such object, or it belongs to the other mode.
422 Validation Error
429 Rate limited. Back off and retry.
Request · curl 
curl -X POST https://api.billkit.eu/v1/subscriptions/sub_9XKp2vQ1/preview_update \
  -H "Authorization: Bearer $BILLKIT_SECRET_KEY" \
  -H "Content-Type: application/json" \
  -d '{"target_price_id":"price_9XKp2vQ1"}'
Response · 200 OK 
{
  "charge_cents": 1900,
  "charge_net_cents": 1900,
  "charge_tax_cents": 1900,
  "credit_cents": 1900,
  "currency": "EUR",
  "new_period_end": 0,
  "proration_at": 1789392000,
  "refusal_reason": "string",
  "refused": false,
  "target_price_cents": 1900,
  "target_price_id": "price_9XKp2vQ1"
}