Change the date to fiscal year

I want to write a function in Excel to change the date. The logic is like this: if the month is (Jan, Feb or March) the result show me one year past (-1 year) and if the month is (April to -December) the result show the current year (which year the date shows).

example: if date is 02,Jan,2012 the result show me 2011 else show me 2012.