declare

@datetime datetimeoffset = '2012-10-25 00:00:00.000 +04:30'

select

case

when (DATEPART(TZ, @datetime) <> 0 and DATEPART(TZ, @datetime) is not null OR CONVERT(TIME(0),@datetime) <> '00:00:00')

then 0

when (DATEPART(TZ, @datetime) = 0 and @datetime <> '')

then 1

when (DATEPART(TZ, @datetime) is null)

then NULL

end as Precision