Preview a prorated plan change

🔍 How to use the "Try It" feature

Step	Description
1. Provide basic auth credentials	Locate the CREDENTIALS section to the right. Enter your username and password for basic authentication. Ensure the credentials are correctly input to authenticate your requests.
2. Choose a request example	If multiple request examples exist, select one from the EXAMPLES drop-down menu. The request body updates automatically based on your selection.
3. Edit parameters	Edit the JSON fields listed under the BODY PARAMS section. When you add a new value, the example value will be overridden. Your changes update the request preview instantly
4. Send the request	Click Try It! to submit the request and view the response body below.

📘 Request body examples and use cases

Select a request body example

All of the request body examples listed below can be selected from the EXAMPLES drop-down menu in the top-right corner of the Try It! feature.

Request Body Example	Use Case
Estimate Subscription	Estimate the total cost of a subscription, including the base product, add-ons, pricing in multiple currencies, proration, and applied coupons.
Upgrade Plan	Upgrade a subscription from a lower-tier plan (e.g., "basic") to a higher-tier premium plan.
Downgrade Plan	Downgrade a subscription from a higher-tier plan (e.g., "premium") to a lower-tier basic plan.
Add-On Quantity Change	Increase the quantity of an existing add-on in a subscription.
Complex Subscription Change	Modify multiple aspects of a subscription at the same time, including: Updating the plan’s quantity and price Adjusting add-on quantities and prices Applying discounts to new or existing add-ons Getting an updated cost estimate

🛑 Error handling

This table lists errors you may run into when working with this endpoint and solutions to help you troubleshoot.

Status Code	Error Message	Solution
`400`	`Request must contain a single root object.`	Ensure the request payload contains a single root object.
`400`	`Request must contain a subscription ID.`	Ensure the `subscription` ID is included in your request payload.
`400`	`Proration is not allowed for this subscription.`	Check the subscription's eligibility for proration.
`400`	`Refund exceeds the last charge amount.`	Ensure the refund amount does not exceed the last charge amount.
`404`	`Subscription ID does not exist: [subscriptionId]`	Verify the `subscription` ID is correct and exists.
`500`	`Subscription is not changeable`	Verify that the `subscription`ID is changeable, or try again with a different subscription.