On an update product amendment quote,Quote metrics total is not calculated as expected

[Manojna]

When creating an update product amendmnet quote on an annual charge with the below factors, Quote metrics total is not calcualted as expected

Billing period - annual

List price base is 0.41/month, quantity - 1500

Billing day of the charge - Default from customer account( Bill cycle day is 1)
Billing period alignment - Algin to charge
Trigger condition of the charge is upon a specific  date (07/05/2018 )

Total should be  .=  0.41*1500*12 months= 7380

But total is shown as 7381.49 

[Manojna · Accepted solution]

Quote metrics computation is based on multiple factors like Billing period alignment , billing period, Bill cycle day, effective start day of the charge 

Below is the Zuora calculation considering all the above  factors of the charge .charge is annual and the bill cycle day of customer is 1 . But the effective start date of the charge on amendmnet  is 07/05/2019

Hence, it is prorated as below

"ServiceStartDate": "2019-07-05", 
"ServiceEndDate": "2019-07-31", 

The above annual charge falls in the period 07/05/2018 - 07/05/2019  - 365 days

For 365 days - 615*12
For 27 days - ((615*12)*27)/365 = 545.92

"ServiceStartDate": "2019-08-01", 
"ServiceEndDate": "2020-07-04", 
 
The above charge falls in the period 07/05/19 - 07/05/20 - 366 days(leap year)

For 366 days (leap year)- 615*12
for 339 days(08/01/2019 - 07/04/2020) = ((615*12)*339)/366 = 6835.57,
So total would be 545.92+6835.57 = 7381.49