Advance tax instalment schedule revised to equal instalments with shifted due dates and conditional board extension. Advance tax must be paid in equal instalments with due dates determined by whether most income arises from sources whose previous year ends by 31 December; the Board may, by notification and conditions, allow specified classes to defer the final instalment. 'Total income' for advance tax means the income used in the Income tax Officer's order or the assessee's estimate, in either case reduced by any capital gains. Other statutory due dates are adjusted to mid month.