How can I take a deposit and then an additional charge?

I am trying to create a seamless experience for my customer in which they enter one credit card and it charges them $100 as a deposit and then, at a later date, an additional amount that they agree upon. How do I do this?

Is the product/service you are offering are on subscription method (recurring payment)? If yes, you can setup your payment field to "Sell Subscription" so the charge will be recurring.

For more information, you can check this article: How to Setup a Recurring Payment Option

If the product/service you are offering are not on subscription method and you want to take an initial charge/payment then at a later date charge an additional amount to your user (two-time payment), you will need to create two separate forms form this. One for the initial payment and the other for the additional charge. You can add the link to your second form to the autoresponder of the first form, so your user can know where to access the second form. For more information about autoresponder, you can check this article: Setting Up an Autoresponder Email.