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POST
/
v1
/
billing.preview_update
Typescript (SDK)
import { Autumn } from 'autumn-js'

const autumn = new Autumn()

const result = await autumn.billing.previewUpdate({
  customerId: "cus_123",
  planId: "pro_plan",
  featureQuantities: [
    {
      featureId: "seats",
      quantity: 15,
    },
  ],
});
{
  "customerId": "charles",
  "lineItems": [
    {
      "title": "Pro seed",
      "description": "Pro seed - Base Price (from 18 Feb 2026 to 18 Mar 2026)",
      "amount": 20,
      "discounts": []
    }
  ],
  "total": 20,
  "currency": "usd"
}

​
Body Parameters

​
Response

{
  "customerId": "charles",
  "lineItems": [
    {
      "title": "Pro seed",
      "description": "Pro seed - Base Price (from 18 Feb 2026 to 18 Mar 2026)",
      "amount": 20,
      "discounts": []
    }
  ],
  "total": 20,
  "currency": "usd"
}

Authorizations

​
Authorization
string
header
required

Bearer authentication header of the form Bearer <token>, where <token> is your auth token.

Headers

​
x-api-version
string
default:2.1
required

Body

application/json
​
customer_id
string
required

The ID of the customer to attach the plan to.

​
plan_id
string
required

The ID of the plan.

​
entity_id
string

The ID of the entity to attach the plan to.

​
feature_quantities
FeatureQuantity · object[]

If this plan contains prepaid features, use this field to specify the quantity of each prepaid feature. This quantity includes the included amount and billing units defined when setting up the plan.

​
version
number

The version of the plan to attach.

​
customize
object

Customize the plan to attach. Can override the price, items, free trial, or a combination.

​
invoice_mode
object

Invoice mode creates a draft or open invoice and sends it to the customer, instead of charging their card immediately. This uses Stripe's send_invoice collection method.

​
proration_behavior
enum<string>

How to handle proration when updating an existing subscription. 'prorate_immediately' charges/credits prorated amounts now, 'none' skips creating any charges.

Available options:
prorate_immediately,
none
​
cancel_action
enum<string>

Action to perform for cancellation. 'cancel_immediately' cancels now with prorated refund, 'cancel_end_of_cycle' cancels at period end, 'uncancel' reverses a pending cancellation.

Available options:
cancel_immediately,
cancel_end_of_cycle,
uncancel

Response

200 - application/json

OK

​
customer_id
string
required

The ID of the customer.

​
line_items
object[]
required

List of line items for the current billing period.

​
total
number
required

The total amount in cents for the current billing period.

​
currency
string
required

The three-letter ISO currency code (e.g., 'usd').

​
next_cycle
object

Preview of the next billing cycle, if applicable. This shows what the customer will be charged in subsequent cycles.