If customers are required to make payments on a certain payment schedule, you can setup these entries on the Payment Schedule page. Add entries for each payment required (e.g. upon contract signing, upon delivery of materials, upon project completion).
Once you've entered the various payments, you can go back in and change the description or percentages. With every change/addition, SmartBuild will recalculate the percentage in the last entry of the list. SmartBuild will not allow you to change the percentage of the last entry in the list. This guarantees that the total of the percentages in the list will total to 100%.