Yes, Advance tax is also payable on Capital Gains and casual income (i.e. income from lotteries, crossword puzzles etc.). As it is not possible to estimate at beginning of the financial year, and if such income arises after the due date of any instalment of Advance tax, then it has to be paid in remaining instalments before due date. If it is paid before the due date then there will be no interest for late payment of Advance tax.