it equals one, i'm not crazy man... but i'm saying it should equal two, april + may... MONTH part should not be calculated by 5-4

okay maybe this might help explain my logic... I stand on-top of my soap-box on 4-01-2015, and again on 5-01-2015, how many times did I stand on my soap-box for the aggregated months...... if you don't say two, i need to start asking for some serious code reviews.

so for you math peeps, lets say I'm calculating the total payment of a loan using datediff, i enter the start date of the loan, and the end date, with the current logic the debtor get a free month... I know logic would need to be introduced to account for day, but just at its simplest form......datediff(m,start,end)*min_payment = total

anyways......

```
----------------------------------------------------------------
----------------------------------------------------------------
DECLARE @INITIAL_NEXT_DUE DATE = '2015-07-06',
@TOTAL_PAY_PLUS_DIF MONEY = 324.25,
@D DATE = CAST(GETDATE() AS DATE),
@MIN_DUE MONEY = 323.23,@UNO INT = 1,@ERO INT = 0;
----------------------------------------------------------------
SELECT
--
--THIS PART CHECKS THE DAY TO SEE IF A PAYMENT SHOULD APPLY,
--A 1 WILL THEN BE MULTIPLIED BY THE MIN_DUE
--
CASE WHEN
(DATEPART(MONTH,GETDATE())-DATEPART(MONTH,@INITIAL_NEXT_DUE))
+(DATEPART(DAY,GETDATE())-DATEPART(DAY,@INITIAL_NEXT_DUE))
+(DATEPART(YEAR,GETDATE())-DATEPART(YEAR,@INITIAL_NEXT_DUE))
>DATEPART(DAY,@INITIAL_NEXT_DUE) THEN @UNO ELSE @ERO
END*@MIN_DUE
--
--THIS PART TAKES THE DIFFERENCE BETWEEN NOW AND THE SEED DATE
--TIMES THE MIN_DUE TO ADD BY THE ABOVE TO GET THE DUE AMOUNT
--
+(DATEDIFF(MONTH,@INITIAL_NEXT_DUE,@D)*@MIN_DUE)
--
--NOW SUBTRACT THE TOTAL PAID TO GET THE CURRENT DUE
--
-@TOTAL_PAY_PLUS_DIF AS [Billing.Next_Due_Amt]
```