There are two ways repeat bookings will be invoiced depending on your pre-existing invoicing settings:
If you have 'Apply any additional charges' set to 'On a new invoice, due today' in the drop-down on your Invoicing Settings page (Settings > Invoicing), users will be charged for the first booking today, and every subsequent booking is billed at the end of each booking.
If you have 'Apply any additional charges' set to 'On next month's invoice' in the drop-down on your Invoicing Settings page (Settings > Invoicing), users are billed for the first booking on the next billing date, and the cost of subsequent bookings will be calculated as soon as they end with the charges going to a pending invoice.
Either way, users won’t be charged for subsequent bookings until those bookings have ended.
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