- JotForm Support
**Jan**This is possible by using the Form Calculation widget and passing the value to the payment tool.

I created a demo form, here's the link: https://form.jotform.com/63545163299969. You can clone it if you like to. Here's a guide on how I created that demo form:

1. I used a regular text box for the donation amount field and then 2 form calculation widgets.

2. Here's the formula for the "+3%" field: Donation Field * .03

3. Here's the formula for the "Total Amount" field: Donation field + 3% field

4. After that, you can just pass the "Total Amount" field in the payment wizard. This option is under the Payment Type Options inside the wizard. You need to change the Payment Type to "Collect Donations" and then the Get Price From to "totalAmount".

Related guides:

https://www.jotform.com/help/259-How-to-Perform-Form-Calculation-Using-a-Widget

https://www.jotform.com/help/275-How-to-Pass-a-Calculation-to-a-Payment-FieldHope that helps. Thank you.