How to send a reminder email to customers who made a deposit vs paying full amount

If a guest chooses a deposit versus a full amount, is there a way I can set a notifier to remind them a balance is due?  Is there a way to make it an automatic payment at a later date?  (We use PayPal)

I am also having trouble getting a number to input into the PayPal box.  I can get calculations into other boxes; what am I doing wrong?

You do not seem to have any form calculations on your form - a value can be automatically passed to the payment field only from a calculation. This is how to perform a form calculation:

https://www.jotform.com/help/259-How-to-perform-calculation-in-the-form

And the following guide explains how to forward the calculated value to the payment field:

https://www.jotform.com/help/275-How-to-pass-a-calculation-to-a-payment-field

When it comes to making only a partial payment and then reminding about and charging the user later on for the remainder sum, I'm afraid this cannot be automated with our system at the moment. What we can do instead, is only remind the user they should make a subsequent payment.

In order to do this, we should set up an additional Autoresponder email:

https://www.jotform.com/help/26-Creating-a-Form-Autoresponder

When setting it up, switch to its Advanced tab, and set its Send Emails Later option to your desired reminder date:

On the initial Emails tab of the Autoresponder, simply write your own message to the user - that it is a reminder they should pay their remaining sum before the event. Now you will have an autoresponding message that is emailed to your users on a certain date before the event, and the only thing left is to make sure that your users who pay the full sum do not receive this reminder.

To do this, we will have to use Conditional Logic:

https://www.jotform.com/help/57-Smart-Forms-Using-Conditional-Logic

Based on how you will be calculating the amount of deposit vs the full price, simply make sure to set up a conditional rule for sending the second autoresponder email only if deposits are selected.

If you need any further assistance, please let us know. Thank you.

Good News. This feature is available now. You can check the further details on the following user guide:

https://www.jotform.com/help/541-How-to-Set-Reminder-Emails-for-Your-Forms

However, this feature does not check if the recipient fills the form or not. If the recipient fills your form and if you do not want that recipient to receive reminder email, you need to delete that recipient from the setting. 

Feel free to let us know if you have further details.