Set up Weekly Invoicing for evergreen subscriptions in Salesforce Billing

The following setup uses Flows, Bill Through Date Override, Override Next Billing Date, and Evergreen Subscriptions to create a subscription that is invoiced weekly. 

Limitations:

• It is required to use Evergreen Subscriptions. The Pending Billing Amount field causes significantly increased complexity for termed subscriptions
• Do not add Weekly (or any other value) to the Billing Frequency Picklist Value Set.
• This does not work for Usage Based Products unless there is additional customization to create weekly usage summaries. 
• Proration Day of Month should not be used or should be set to the same date as the start date.
• Pricing limitations are discussed at the bottom. 

Setup:
Add a field to the Order Product to indicate a weekly invoiced subscription. If needed, add the same field to the Quote Line and Product so it twins to the Order Product. See Mapping Custom Fields Between Objects. For this set up, use a Checkbox field called Weekly Invoicing where True indicates a weekly invoiced product.

Set up the Product as follows:

• Subscription Pricing = Fixed Price.
• Subscription Term = 1.
• Subscription Type = Evergreen.
• Billing Frequency = Monthly. 
• Charge Type = Recurring.
• Billing Type = Advance.
• Weekly Invoicing = True.
• Billing Rule, Tax Rule and Revenue Recognition Rule as per your specific needs.
• Note that the pricing reflects the weekly price.   

Flows:

1. Create a Record Triggered Flow that is triggered when the Order Product is created and is Optimized for Actions and Related Records:
   1. The Weekly Invoicing field is True and the Billing Frequency does not equal Invoice Plan
   2. The Flow should update the Bill Through Override Date to Start Date + 6 days. More complex date arithmetic can be used, if desired, to set this up so that the Invoices occur on a specific day of the week.
2. Create a Record Triggered Flow that is triggered when the Order Product is Updated with the Condition that Last Charge to Date is not null and Weekly Invoicing is True. Select the option to run Every time a record is updated and meets the condition requirements. Optimize the Actions and Related Records. This Flow updates:
   1. Bill Through Override Date to Last Charge to Date + 7 days
   2. Override Next Billing Date to Last Charge to Date + 1 day

Pricing:
If the desired outcome is a consistent price week to week, then set the Billing Configuration Settings for Proration Type to either 30 Days or Monthly (CPQ Formula). The setting Calendar Days cause small variations week to week depending on the number of days in the month. Note that this is a global setting and affects all proration in your org.

To price a product based on a weekly price, set up an effective daily price. Use the Proration Type setting = 30 Days and set the Product up this way:
-Subscription Term= 1  
-Subscription Pricing = Fixed Price
-Subscription Type    = Evergreen
-Standard Price = [Daily Price x 30]. Note that because we are working around the existing billing frequency we are actually setting the 30-day price for a 30-day period. In other words, setting the standard price to 300.00 returns a weekly price of 70.00. 

If you want to show the weekly price to your users in the Quote Line editor, create and expose a custom formula field with the formula: 

[Net Total * (7/30)]

Validation Rule:
Consider setting up a validation rule on the Product that enforces the correct setup for a weekly product.   

Testing:
Build this out in a full sandbox and test thoroughly before pushing to production to make sure your implementation works as expected with this setup. 
Suggested tests include Bill Now, Invoice Schedulers, and Cancel and Rebill.