Formula For Calculating Partial Year Interest

I have developed a financial calculator that asks the user for the "input date" which is used to record balances as of the input date. My interest calculation for the first year is based on the current date compared to the input date. For example, if the user is keying in a current balance of 10,000 @ 10% interest, and the "statement date" or "input date" is 12/30/2013, and the current date is today, 2/4/2014, then it should calculate interest for the entire year of 2014. It is not doing that. It calculates $3 interest.

But if input date is 6/30/2013 with current date of 2/4/2014, it seems to work OK. It calculates interest of $504 in that case. It appears to get messed up with the year transition between current date and input date. The formulas I have listed below appear to work fine except when the input date is 2013 for the year and the current date is 2014. The formula does not "see" that input date was last year. There must be a minor tweak to formula I am overlooking.

Cell C2 = Today's Date=TODAY()
Cell C3 = Input date (user keys in date in mm/dd/yyyy format)
Cell E2 = "translate input date to year format" =DATE(YEAR(C3),12,31)-C3
Cell E3 = Investment Rate
Cell G2 = yr 1 interest rate adjusted =(E3/1)*($E$2/365)
Cell C21 = Current Balance
Cell D21 = Interest Yr1 = C21*G2

I need the interest calculation to account for partial year accrual.