STCG on sale of securities is not exempt and taxable at flat rate of 15% u/s.111A. It is to be included in Gross Toal Income. But one thing, even if you are in 10% slab after including capital gain with Salary, you need to pay tax @ 15% on such STCG. for e.g. if you have salary income of Rs.3,00,000 and STCG of Rs.1,00,000. Deduction from 80C to 80U available to you are 3,50,000. then Tax liablility will be as follows.
Income from Salary = 3,00,000
Income form STCG u/s.111A = 1,00,000
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Gross Total Income = 4,00,000
Less: Deductions u/s.80C to 80U =(3,00,000) (Since Chapter VIA deductions are not available ---------------- against LTCG u/s.112 and STCG u/s.111A)
Net Taxable Income 1,00,000
Tax on above: 1,00,000* 15% =15,000 (Even you are in 2,50,000-5,00,000 slab, your income u/s.111A taxable @ 15%)
Add: Cess @ 3% = 450 --------------
Net Tax Liability = 15,450
Note: You should using basic exemption limit against LTCG/STCG after utilising for all other souces of Income.