ITR processed with Demand

The extended due date for filing ITR for AY 2020-21 was 10.01.2021.

I filed ITR ON 10.01.2021. i received ITRV for the same. Tax payable was Rs. 11500/

I could not pay tax on  10.01.2021 because of my financial problems. 

Later, on 18.03.2021, Paid the Tax Rs. 11500/- i filed revised return.I duly filled the necessary challan details in ITR before submitting it. My ITR showed Refund amount and Tax Payable amount as nil
But after the return was processed, I got the Demand of Rs.10,300/- and odd. Out of which Rs. 10,000/- was charged as late fee u/s 234F and remaining amount was charged as interest in delay of filing u/s 234A.

How they can charge u/s 234A and 234F when the original return was filed on the due date?