Taxable income

In the present case , your tax liability will be only on your lottery winnings at flat 30% i.e. 26000×30% = 7800  Minus rebate u/s 87A =2000. Total tax = 5800 + 3%= 5974.

As per section 112 (1)(a), benefit is given in case of LTCG if total income is less than the exemption limit where you can deduct the unavailed exemption ftom the LTCG and tax @ 20% will be payable only on balance amount. 

In your case , the entire 20000 will be deducted. However, please note that the above exemption is not on winnings ftom lottery which are taxed flatly @ 30%. 

Sir, here I have assumed that the assessee is an individual. Total income is within the exemption limit. That is the reason why LTCG is also not taxable here. Otherwise it would also have been taxed @ 20%.