When does apple request payment for AppleCare+ Replacement device?

I have an iPhone Xr that my brother is going to give me the money for to send to apple to get replaced. Originally we were going to do a battery replacement but sadly the back got cracked and that means full device replacement. Since I have AppleCare+ on the device I know the device replacement cost should be $100 + tax. What I want to know is when does apple request payment? Do I send it off and they get the phone then request payment? First time doing this so would like to know in advance.