defining a years length(start and end dates)

hi
i am updating a work calculator. i am stuck. the problem is the new rates for 2008 came into effect from 31-dec-2007, so i have to have the rates for 2007 to stop on 30-12-07.and 2008 to kick in when the 31-dec-07 is entered.i am doing this through the excel macro visual basic editor.

any help on this code is appriciated

ronan

p.s. if you need the program email me at barbarian006@hotmail.com