Custom: If past date is selected then a negative invoice for the prorated amount gets created along with a positive invoice with the prorated amount. Let’s consider another example where the annual subscription of the product is from Jan 2021 to Dec 2021 and the customer has increased the subscriber count of the product from 50 to 100 on current date ( 22nd August) which will increase the subscription amount from 600 to 1200. Now, due to company policy, the invoice is generated for 20th August, which is back dated. Hence, both negative and positive invoice is generated for the remaining period i.e. from 20/08/2021 to 31/12/2021.