Hi!
You need to use the daily effective interest rate.
If you have a base of an APR12 (Nominal compounded monthly) use:
=(1+APR/12)^(12/365)-1
If you have a base of an annual effective use:
=(1+AnnEff)^(1/365)-1
Assuming dates in column A1 down, Flow in column B down, Interest in
column C down and Balance in column D down:
C1: 0
D1:
=B1
C2:
=D1*((1+DailyEff)^(A2-$A$1)-1)
D2:
=D1+B2+C2
Now select C2 and D2
Copy down parallel to the flows in column B