Calculating the Billing Interval for a dues billing run

The billing interval for a dues billing run is based upon a specific customer's Renew Months as defined on the Manage customers window's Financial tab (if non-zero) or the default Standard Billing Interval defined on the Set up general options window (from Billing, select Set up module > General options). However, in the case of an annual dues billing cycle, prorating factors may affect the calculated interval.

Note: All line items billed on a dues bill have the same interval.

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Billing interval for anniversary dues billing cycle
Billing interval for annual dues billing cycle