Flex gives you granular control over how invoices are generated, displayed, and edited across your organization. These general invoicing settings help align billing behavior with your financial policies, tax rules, and accounting integrations.
This article explains how to configure proration logic, manage $0.00 line items, control cross-location credit notes, and define which invoice types admins can edit or delete.
General invoicing settings
To configure these settings, go to 
Settings > Billing > Invoicing.
Proration
Proration is used for members who join your space after the billing date. In such cases, the system will prorate the amount the customer owes based on the number of days they spend with you during that month.
Depending on which invoice should be prorated, you have two options: either prorate the first invoice the customer will receive or the second one. Learn more about proration and how it works →
You can also choose how the system will calculate the proration. You can use the Average Month Length (365 / 12 = 30.42 days) or the Current month length (for example, 31 for March, 30 for April, 28 for February).
$0.00 Line Item Settings
An invoice can include line items priced at $0.00. The following two options could be used if an admin wants to filter the $0.00 priced invoices and wants to allow generating an invoice with a total value of $0.00:
Filter invoice line items with a $0.00 total – Any line item priced at $0.00 will not be added when generating an invoice with fees and memberships. The system would create invoices with fees and memberships, and the $0.00 amount would not appear, as it would be filtered out.
Enable creating invoices with a $0.00 total amount – An invoice can be generated with a total or sum of $0.00.
Important: Do not select both, as this would prevent admins from creating invoices priced at $0.00 and would generate an error.
Display plan % discounts as negative amount line items – Displays plan discounts as negative line items on invoices.
Credit notes can be allocated to invoices from other locations
By default, you cannot allocate a Credit Note created in one location to an invoice in another location. However, if you select this checkbox, the system will allow you to allocate a Credit Note created in location A to an invoice in location B.
Determine which invoices can be edited and deleted
Scroll down to the We'll let you edit and delete the following types of Invoices section. Select the checkboxes to let admins edit and delete paid, sent, and voided invoices. Please ensure this complies with your country's laws before making any changes.
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