HugoRS

[earnest quiver]

Hi there

You basically let us do this for you.

Are you asking how to calculate ahead of time?

[storm perch]

Alright, thats a release

Yes. For our own checkout

I'm using the Retrieve the subscription api to get the users current plan

And then I'm using the Retrieve a price API for the new subscription

Is this the way

[earnest quiver]

If you want to know what the proration will be ahead of actually making the update then you want to use the Upcoming Invoice API: https://stripe.com/docs/api/invoices/upcoming

[storm perch]

But can I use the upcoming invoice api before switching the subscription plan?

[earnest quiver]

Yep

Take a read through what it says there in the API Ref for how that endpoint works

[storm perch]

Thanks, I will have to send the new subscription id here, but the subscription is not yet created, right?

[earnest quiver]

Well if you are previewing an update then the Subscription has been created? Otherwise you can also preview the initial invoice for a new Subscription before creating it

[storm perch]

But right now i'm only using the update subscription API and this will change the users subscription directly (and also create a new subscription id, right?) I want to display the information before the switch.

[earnest quiver]

No updating a Subscription does not create a new Subscription ID

Once a Subscription is created then it will maintain the same Subscription ID throughout its lifecycle

[storm perch]

Alright cool, but how does the retrieve an upcoming invoice know what price the new subscription has?

[earnest quiver]

You use the subscription_items parameter to indicate what items you want to add or update.

[storm perch]

Now I understand, and where do I grab the subscription_item from?

[earnest quiver]

You would get the current ones by retrieving the Subscription using https://stripe.com/docs/api/subscriptions/retrieve

[storm perch]

Alright, thank you!