Tips on Billing a client while keeping the first year 20% for yourself.

I’m just wondering people pocket the first year circle discount when billing a client. Do you invoice them every year for the hosting yourself or ask for a credit card and handover the website to them? I can see in some instances you may contract regular maintenance and content creation for a client in which you bill them a monthly fee. But if it is something simple that you want to hand over, fo you pass the discount to the client or keep it?