Advance tax is payable on total income which includes capital gains and casual income (i.e., income from lotteries, crossword puzzles, etc.).
However, it is practically not possible to estimate the income from capital gain and casual income in advance. Therefore, in such cases it is provided that if any such income arises after the due date of any installment, then the remaining tax calculated on capital gain and casual income shall be paid in remaining installments of capital gains which are due.
If the entire amount of tax is so paid then no interest for late payment is levied.