[#7181] Incorrect pro rated amount

Hi guys,
I've had 3 members go through an upgrade process and the prorated amount is not correct. Here is the hypothetical:

Member is subscribed to a monthly plan = $40/month
Member upgrades to a yearly plan approx. 1/2 way into their month = $800/year
Member is provided a 50% discount code = should reduce the 50% from 800 & further reduce their prorated amount = 400-20 = $380

However the amount would come up to something like $310. Please bear in mind these are hypothetical numbers but the scenario is the same. The coupon code is working as expected but the proration isn't. We can tell this because of the following which is on the user's invoice:
"USD 800.00 per year The first payment of the upgrade for 1 year, taking in account your current subscription, is USD 704.00 instead of USD 800.00."

Then following that, it will display the discount, then it will show the discount being reduced from the above incorrectly prorated amount. I hope the hypothetical helped and realize there are variables. If you'd like specifics or would like further details, I'd be happy to provide that via private chat or email. Thank you!

To analyze you need to always start from the current active subscription startpoint and think of:
a. what the subscriber paid originally (after discounts/promotions) to purchase the subscription. E.g., $40 for 1 month (30 days)
b. how many days are left in the current paid subscription. E.g., 20 days left (10 days into current subscription)

The risidual value is then 40 x ( 20 / 30) = 26,66

The risidual value is then subtracted from the new cost to calculate the upgrade cost and after that any new discounts will be applied.

Thank you for the reply and the prorating makes complete sense to me. However what I am trying to say is that the user got more than their entire previous month's amount reduced + more, and they had already used up approx half their previous month. So clearly that is not correct.
Could you please assist me further to see for yourself? I am happy to help in anyway I can, but need to find the issue so it doesn't happen again. Each of these members have been active for multiple months so maybe it was reducing an amount from multiple months (of course this should not happen)? I am only speculating as I do not know, but I do know the amount is wrong. Thank you kindly!

You'll need to provide exact numbers for us to run the math. The prorating takes the remaining value of their subscription based off the time they did not use and subtracts it from their upgrade plan. See the below similar topic where this is explained in detail.

www.joomlapolis.com/forum/255-developer-members-support/239084-upgrade-plan-renewal-date-has-changed-and-value-goes-up?start=6#304354

Yes, I am completely aware of how pro rating works. As I stated, the amount is not correct and far from it.
I will pm you the exact numbers.

Based off the numbers you provided the math comes out as follows with 1 day used from their current subscription.

Current Plan: $15/mo
New Plan: $199/year
Promotion: $79

Per day Value: 15 / 30 = 0.5
Used Value: 0.5 x 1 = 0.5
Credit: 15 - 0.5 = 14.5
Prorated Upgrade: 199 - 14.5 = 184.5

So before any discounts are applied they should have a price of $184.5. This assumes only 1 day has been used of a 1 month subscription. If they've renewed in advance then they'll of course get further discounts. Below is after the discount has been applied.

Discounted Upgrade: 184.5 - 79 = 105.5

So in the end they'd be charged $105.5. The big thing that changes all of this is actually how much value they have left in their subscription. If they renewed in advance by 1 month for example they've 59 days of value to be credited towards their upgrade. You provided the user is seeing a value of $40.301, which suggests they've more time purchased than 1 month. Looks like almost 3 months worth of time. Did they renew in advance? These calculations are based off how much time they have left between the time of upgrading and when they expire.