Beginning and End of month calculation

DECLARE @MonthBegin as datetime
DECLARE @MonthEnd as datetime

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

SET @MonthBegin = DateAdd(m,-1, @MonthBegin)
SET @MonthEnd = DateAdd(ss,-1,DateAdd(m,1, @MonthBegin))

SELECT @MonthBegin as 'MonthBegin'
, @MonthEnd as 'MonthEnd'