---
title: "Proration preview of a plan change: what is charged now and what changes (billing:read)"
method: POST
path: "/billing/subscription/preview"
tags: ["Billing"]
---

# Proration preview of a plan change: what is charged now and what changes (billing:read)

`POST /billing/subscription/preview`

## Request

- Base URL: `https://hostingsurge.com/api/v1`
- URL: `https://hostingsurge.com/api/v1/billing/subscription/preview`
- Auth: one of:
  - HTTP bearer
  - API key in cookie `__Host-hs_session`

## Query parameters

- `orgId` string: Organization id (required when you belong to several)
- `lang` 'en' | 'sv': Language of labels and Stripe pages (default en)

## Request body

- object
  - `planId` 'free' | 'pro' | 'business', required
  - `interval` 'month' | 'year'

## Response `200`

Preview

- object
  - `planId` 'free' | 'pro' | 'business', required
  - `interval` 'month' | 'year', required
  - `change` 'upgrade' | 'downgrade' | 'interval' | 'cancel' | 'resume' | 'none', required
  - `effective` 'immediately' | 'period_end', required
  - `prorationDate` integer, nullable, required: unix seconds; send it back when confirming so the charge matches this preview
  - `currency` string, required
  - `amountDueNow` integer, required: charged right away (upgrades are invoiced immediately; downgrades become a credit on the next invoice)
  - `subtotal` integer, required: minor units (cents)
  - `tax` integer, nullable, required: minor units (cents)
  - `total` integer, required: minor units (cents)
  - `lines` object[], required
    - `description` string, nullable, required
    - `amount` integer, required: minor units (cents)
    - `proration` boolean, required
    - `periodStart` string, nullable, required: ISO-8601 timestamp
    - `periodEnd` string, nullable, required: ISO-8601 timestamp
  - `trial` boolean, required: the subscription is in its free trial: nothing is charged until it ends

## Other responses

- `400`: Invalid request (code invalid_request)
- `401`: Missing or invalid session/token (code unauthorized)
- `403`: Authenticated but not permitted (code forbidden); details.requiresSession for plan/payment changes over a token
- `404`: Not found or not visible to the caller (code not_found)
- `409`: Conflicting state, e.g. a subscription already exists (code conflict)
- `429`: Too many requests (code rate_limited); see Retry-After
- `501`: Billing is not set up on this server (code not_configured)
- `503`: The payment provider is unavailable (code provider_unavailable)

---

[API](https://skmtc.dev/hostingsurge/apis/hostingsurge-platform-api.md) · [All operations](https://skmtc.dev/hostingsurge/apis/hostingsurge-platform-api/llms.txt) · [OpenAPI document](https://skmtc.dev/hostingsurge/apis/hostingsurge-platform-api/revisions/4d08337cdff1?raw)