Do all Splitit plans work in the same way?

No, the way Splitit works varies from retailer to retailer, depending on their payment processor.

However, for all plans; in addition to your monthly installments, the full outstanding amount is usually authorized (held) on your card to guarantee future payments. These authorizations may be temporary (up to 30 days) or they may be required to stay in place for the duration of your plan until it is cleared. Splitit has no control of this as it is determined purely by the payment processor used by the retailer. 

To see exactly how your plan works, log in to the shopper portal and under 'Plan Details' click on 'How Splitit Works?'. This will take you to a detailed explanation of your particular plan.