The I. Tax Act provides that assets should be put to use for more than 180 days to claim full depreciation. So point is 180 days not six months or half year.
If asset is put to use on or after 4th october then you end up in using the asset for a period less than 180 days.
If asset is put to use on or before 3rd October then you would have used it 180 days or more
In case of leap year even asset put to use on 4th october will be used for 180 days.
IF YOU TAKE 30TH SEPT AS THE CUT-OFF DATE, THE INCOME TAX ASSESSING OFFICER WILL NOT HAVE ANY PROBLEM. HE WOULD BE THE 1ST PERSON TO ACCEPT IT, AS YOU WOULD BE CLAIMING LESS DEPRECIATION TO THAT EXTENT. IN OTHER WORDS YOU WOULD BE PROVIDING 50% DEP. ON ASSETS PURCHASED BETWEEN 1ST TO 3RD OCTOBER, WEREAS YOU COULD HAVE CLAIMED 100% LEGALLY. CONSEQUENTLY OVER-STATING YOUR INCOME TO THAT EFFECT AND PAYING TAX THEREUPON AND THEREBY PUTTING YOUR CLIENT AT LOSS.