When filing for your 1702Q in Taxumo, you will eventually encounter this field:
If you have overpayments from your Annual ITR (1702RT) the previous year, you input that amount in this field.
Overpayments are indicated by the amount enclosed in parenthesis. It's also important to note that the option "To be carried over as tax credit for the next year/quarter" must be selected. These are the two (2) conditions in order to apply for excess credits.
If the amount is not enclosed in parenthesis, then it's not an overpayment. You'll have to input ZERO since you don't have any excess credits.
If this is the first time you are filing for your 1702Q ever, you can simply input 0 in this field.