Persons leaving India: income from the pre-departure period is taxable in the current assessment year; officer may demand rapid return. When the Assessing Officer believes an individual will leave India and not return, income from the expiry of the previous year to the probable departure date is chargeable to tax in that assessment year, with separate assessments for each completed previous year or part-year at rates in force; the Assessing Officer may estimate income and may require the individual, by notice, to furnish a return within not less than seven days setting out completed-year and estimated part-year income, and the tax under this section is in addition to tax under other provisions.