help with subscription based service

[dadamssg87]

I'm developing a subscription based web service but i'm having trouble figuring out how to charge/not charge customers when creating their initial subscription or updating.

 

For instance, lets say i have bronze, gold, platinum tiers of subscriptions and i allow the customer to change tiers whenever they choose. I'd like to have my billing occur on the 15th of every month.

 

Obviously i can't just set up to bill the customer's current tier every month alone. Customers could just go in and change their service to bronze on the 14th and then change back to platinum on the 16th after they've been charged for bronze service.

 

Should i implement cut-off days to update their service? Pro-rate it?

 

Does anyone know how this sort of thing typically works?

[Philip]

Prorated is typically what happens, at least from my experience. If its within X days of the next bill, just tack on the prorated amount + next months charge. Otherwise, if they step down give them store credit.