How to add a discount code without using products or subscriptions?

I want to add a discount code without using products or subscriptions.

I am using the Form Calculation widget to find out the price and I want to give specific customers discount codes.
Why is that not possible?

You are already using the user defined amount payment type. That means you can pass the total calculation to your "Berechnung" field.

What you can do is create another form calculation widget that calculates the total discount and deduct that discount to "Berechnung" field.

ex.

Check my sample form here https://form.jotform.com/91913509877975. Feel free to clone if you want https://www.jotform.com/help/42-How-to-Clone-an-Existing-Form-from-a-URL.

Let us know if you have any questions or if you need further assistance. 

I understand but how do I put in a list of discount codes with different effects on the price. 



Example:

customer name........... discount code ......... discount effect

ABC ..........................summersale55............-10€

xyz............................xyzSPECIALDEAL..........-20€

blabla........................BLA1907discount..........-10%

As soon as the customer who owns a code and puts it into a text field it should change the price according to the code I set for them previously.