stripe upcoming invoice for same billing cycle in stripe - stripe-payments

Question

I'd like to show a customer a preview (or a quote) of what their subscription charges will be if they make changes to their subscription. For this, I'm using the "upcoming invoice" API endpoint:
https://stripe.com/docs/api/invoices/upcoming
From that link, they state that "You can preview the effects of updating a subscription, including a preview of what proration will take place.".
here is the exapmle
def retrieveUpcomingInvoice(subscriptionId,customerId,nextPriceId):
try:
# Retrieve the subscription
subscription = stripe.Subscription.retrieve(subscriptionId)
# Retrieve the invoice
invoice = stripe.Invoice.upcoming(
customer=customerId,
subscription=subscriptionId,
subscription_items=[
{
'id': subscription['items']['data'][0].id,
'deleted': True,
},
{
'price': nextPriceId,
'deleted': False,
}
],
)
return invoice
except Exception as e:
return str(e)
i got the amount_due for upgrad subscription amount user has to pay but only for different billing cycle
Monthly to monthly subscription "or" yearly to yearly subscription(same billing cycle):
like if i am on monthly basic subscription for $10 and i upgrade the subscription for advance subscription for $30 than invoice in return i got amount_due for $40 which is merged amount of plus and advanced, which is wrong , because i had already paid for 10$, so amount pay should be 30-10 = 20$ (tested: if i pay then 20$ is cut from account) (and invoice show $40 which is wrong)
Monthly subscription to yearly subscription or Vice-versa (this is ok)
if currently i am on monthly basic subscription for 10$ and i upgrade to yearly plus subscription for 100$ then upcoming invoice in amount_due show me correct information which is 90$ (and also if i pay it cut 90$ from account)
so how to get coorect amount in same billing cycle in stripe

Answer 1

You have a subscription for $10 per month, and after 15 days (half of the month) you want to change it to $30. With the upcoming invoice, you get the invoice the customer should pay in the next billing cycle which includes 3 line items:
Unused time: -$5 (that's the initial price divided by two)
Remaining time: +$15 (that's the new price divided by two)
Next invoice: +$30 (the new price for next month)
Here the total is: -$5 + $15 + $30 = $40 to be paid in 15 days. If that's not what you want you could:
Remove the $30 of the next invoice by passing subscription_proration_behavior: "always_invoice".
Or remove the $15 of the remaining time by passing subscription_billing_cycle_anchor: "now"
Note that changing the billing cycle of a subscription from monthly to yearly works differently, as explained here.

Answer 2

reset your billing cycle for get the exact amount
add subscription_billing_cycle_anchor = "now" at getting upcoming invoice
def retrieveUpcomingInvoice(subscriptionId,customerId,nextPriceId):
try:
# Retrieve the subscription
subscription = stripe.Subscription.retrieve(subscriptionId)
# Retrieve the invoice
invoice = stripe.Invoice.upcoming(
customer=customerId,
subscription=subscriptionId,
subscription_items=[
{
'id': subscription['items']['data'][0].id,
'deleted': True,
},
{
'price': nextPriceId,
'deleted': False,
}
],
subscription_billing_cycle_anchor = "now", # add
)
return invoice
except Exception as e:
return str(e)