Calculation based on date field

[REGGIE MAGER]

Good morning,

How would I go about making a calulated field that would automatically fill in an amount due if an invoice has not been paid in 30 days or has been partially paid. I have my date field, Amount due field, amount paid field and Balance due field. Thank you for the help.

[wireshop]

here's how I would do it

BalanceDue=

if(Get(CurrentDate)>(OrderDate+30);AmountDue*FinanceRate;AmountDue)