Penalty on late payment of income tax on a small amount

There was no tax became due on the income of one of my friend in FY 2024-25 but due to Bank Interest, his income increased and now has to pay tax Rs.1605 plus surcharge 64. If he pay it now, how much penalty he will have to pay. Whether penaly will be on Rs.1605 or Rs.1669 (Rs.1605+Rs.64). Secondly paying now in June or paying at the time of filing ITR, most probably in July (as at present prevalidated figures are incomplete in ITR) will make any difference.