|I have just thought of this very quickly, and therefore not sure if it will work, or if there are better options out there. |
What you 'could' do is,
1) select a cell in which you can record todays date (eg A1)
2) type the formula =today()
this will put todays date in that cell eg 17/05/2012
4) right click and select 'format cells'
format a cell using 'Custom' format and in the 'Type' field enter dd
This will only show the DAY in that field now eg 17
everytime you open this workbook it will now update the field so that it will show the current day.
you can now use a formula to test if the value in that field is '1' or '01' and accordingly update the balance.
if you are using vba you can also achieve this, let me know if you are using vba and we can try and help further.
for example if you select cell