Comment on BTST/ATST( Buy/Acquire Today Sell tomorrow)
This thing with BTST is a grey area, best you also consult your CA. The CA guidance note, considers intraday equity as speculative, but in a BTST trade we pay STT as if it were a delivery trade, and also the stocks come into the pool and go out. So I’d say you can consider it as business or STCG.
Yes, that auction penalty can be shown as cost towards transfer of sale in your ITR.