Aging Function

If the invoice date is in column A and the amount outstanding in column B then in col C

=IF(B1>0,+TODAY()-A1,"")

Thank you very much for the previous formula, it worked perfectly!

Now that I have the number of days an invoice is late, I need to move them to another section of the worksheet that breaks it down between current, 30 days, 60 days, 90 days and 120+. I also need it to add the amount due for each amount past due.