The share market is not foolish to give you a dividend without a cost. Although it is Tax free. the dividend comes from your companies pocket and therefore the share price should come down by the extent of dividend. So essentially the net profit is ZERO. So always on the ex dividend date ( date on which you need to hold the share to get one aka closure of registered members.the next day share price falls. Because the market takes cognizant of the payout and therefore corrects the stock price by that amount ans thus making the gain ineffect zero. I guess the esteemed author has forgotten this basic point
