This works,
add 1 month, sub days of date
select convert( datetime,right('00'+convert(varchar(2), month(@date)),2) +
'/' + right('00'+convert(varchar(2), DAY(DATEADD(d, -DAY(DATEADD(m,1,@date)),DATEADD(m,1,@date)))),2) + '/' +
convert(varchar(4),year(@date)))