Hi Kamele, This form is not set up correctly. Please follow the instructions below. Delete the Donation field In the Neartail Edit page, click on the gear icon next to the Donation field > Field settings page will be displayed > click on the trash icon in the bottom left corner to delete this donation field. Similarly delete the Total Amount Due field In the Neartail Edit page, click on the gear icon next to the Total Amount Due field > Field settings page will be displayed > click on the trash icon in the bottom left corner to delete this donation field. Calculate order amount In the Edit page, click on the Add price field button > select Order amount, click Next > select Standard calculation using TOTAL() formula, click Next > click Create. Enable donation option In the Edit page, click on the Add price field button > select Discount, click Next > select User entered amount, click Next > click Create > Donation field will be added and the Field settings page will be displayed > click Answer > click Configure link for the Validation option > Select Number, Is Number option and click Save. Calculate total amount In the Edit page, click on the Add price field button > select Net amount, click Next > select Standard calculation using NETTOTAL() formula, click Next > click Create. Please try this and confirm.