Help Needed With A Query

Hi

   I have a function which returns the periodId from the period table and the function is as follows:

 ALTER FUNCTION [dbo].[udf_Quarter] (@Date datetime)
RETURNS int
AS

BEGIN

DECLARE @month int
SET @month = Month(@Date)
RETURN
CASE
WHEN @month BETWEEN 1 AND 3 THEN 5
WHEN @month BETWEEN 4 AND 6 THEN 6
WHEN @month BETWEEN 7 AND 9 THEN 7
WHEN @month BETWEEN 10 AND 12 THEN 8
END
END

 Which works fine but i want to do the following with it. We produce quarterly statements.. So the user comes in jan or the begining of Feb to upload and process and order Statements from 10/31 to 12/31 the the 4 quarter data.. So Is there a way i can check if the user orders the statement in between jan and feb it has to reture PeriodId 5.

 

Any help will be appreciated.

Regards,

Karen