How do I calc interest using 2 interest rates in 1 calendar year

I am trying to calculate interest using 2 interest rates in 1 calendar year.
Example:
Lets say that from January 1, 2005 through June 30, 2005 the interest rate
is 5 percent and the interest rate from July 1, 2005 through December 31,
2005 is 2 percent. How much interest is due on $1000.00 if the accrual date
starts on 03/01/2005 and is paid on 09/09/2005?
Currently, I have a formula that will calculate interest for a given year as
long as the interest rate does not change mid-year.

Assuming the rates are in B1, B2

=1000*((DATE(2005,6,30)-DATE(2005,1,2))/(DATE(2006,1,1)-DATE(2005,1,1))*B1)+
1000*((DATE(2005,9,9)-DATE(2005,6,30))/(DATE(2006,1,1)-DATE(2005,1,1))*B1)

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HTH

Bob Phillips

"MrTaxGuy" <MrTaxGuy@discussions.microsoft.com> wrote in message
news:BEA17D69-43F1-4A19-8948-C4B879E2E77A@microsoft.com...
> I am trying to calculate interest using 2 interest rates in 1 calendar
year.
> Example:
> Lets say that from January 1, 2005 through June 30, 2005 the interest rate
> is 5 percent and the interest rate from July 1, 2005 through December 31,
> 2005 is 2 percent. How much interest is due on $1000.00 if the accrual
date
> starts on 03/01/2005 and is paid on 09/09/2005?
> Currently, I have a formula that will calculate interest for a given year
as
> long as the interest rate does not change mid-year.