Short term capital gains query

STCGT itself is a income tax above which you only need to add 4% health and education cess. In your case ur calculations are totally wrong. If you need any help tgen please check your inbox.

Please note you have not availed for 115BAC as a result of the fact you are eligible to get deductions from Sec 80C TO SEC 80U
CALCULATE INCOME TAX @ 15%
EDUCESS ARE PART AND PARCEL.

1. U need to pay tax 15% on STCG (after deducting 80C deduction, if any i.e net 8-1.5 =6.5)and on than tax, 4% cess on that tax amount.

2. Deduction u/s 80C to 80U available.
80C up to limit of 1,50,000

3.Tax Calculation is like this.
STCG................8,00,000
80C to U Dedu...1,50,000
Net Income ......6,50,000
Tax* @ 15%........82500
Cess4%.............3300
total Tax..........85800

You have made an excess tax payment if your income for the said FY does not include any other income other than STCG. 

Further deduction u/s 80C up to 80U will be available if you have made the required investments under the the tax saving scheme. 

Provided, STCG is the only source of income for FY 2020-21 without any deduction. The tax will be : 82500+4% Cess = 85800. Hence you have made excess tax payment

Whatever I have mentioned nidhi has followed me.

I thinks Nidhi ma'am is explaining the things in a better or easy to understand way that other members