T-SQL - first day of month

-- Determine the First Day of this current month.  The page calcs cannot be on or after this date.

DECLARE @FirstDayOfThisMonth as datetime

SELECT @FirstDayOfThisMonth = CAST( CAST(Month(GetDate()) as nvarchar(2)) + '/01/' + CAST(Year(GetDate()) as nvarchar(4)) + ' 00:00:00.000' as datetime)

     --SELECT @FirstDayOfThisMonth