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My customers will actually be the ones making the changes to their subscription via the customer portal API. How to make effect the changes to the subscription and collect the payment later?

Summary

In Chargebee, you can allow customers to make changes to the subscription from the customer portal. Example, add addon/change plan.These changes can be made immediately or at the term end and the customer will be charged respectively. 

Currently, it is not possible to apply changes immediately and charge at the term end. However this is possible if you choose to implement this via API.

Note:
1.If you are using our APIs the change subscription action should be initiated from outside of the Chargebee portal. Example, a change subscription button on your end/website.
2.In case of resuming a paused subscription, the customer will be charged immediately if the reactivation occurs out of the current term.

Chargebee’s Self-serve portal

API Process:

1. Provide a click to action page: Example - Change subscription/Update subscription

2. Lists the current subscriptions for the customer where they can make the changes.

3. Use the Update a subscription API and ensure that the changes come into effect immediately. 

4. In order to ensure that the customers are not charged immediately but only on renewal, you can pass the invoice_immediately parameter as "false". 

   1. This ensures that the changes come into effect immediately but the charge is collected only during renewal.

Related articles and Documentation

Can my customers update their payment method information through the Chargebee customer portal?

My customers are unable to see specific plans on the portal. Why?