I prefer the method of using a table to store fiscal period information.

CREATE TABLE [dbo].[fscl_yr_wk]

(

[fscl_yr] [smallint] NULL,

[fscl_yr_wk_nbr] [smallint] NULL,

[fscl_prd_nbr] [smallint] NULL,

[wk_bgn_dt] [datetime] NULL,

[wk_end_dt] [datetime] NULL,

[fscl_mth_wk_nbr] [smallint] NULL,

[fscl_yr_wk_key_val] [nvarchar](6) NULL,

[fscl_prd_key_val] [nvarchar](6) NULL

)

In the data model for this table, fscl_prd_nbr is the fiscal month. With these columns you can derive pretty much any fiscal date information you need. I have created functions that take parameters of fiscal month and/or fiscal year (or use getdate() for functions that return "current" fiscal information).