I have taken itc rs. 27,40,250/- in trans-1 on dated 23.09.2018
Later, we have found mistake in itc taken and debit itc rs. 4,26,432/- in gstr-3-b as on dated 19.12.2018 (by self assessment - not tell us department)
Now, interest liability arises on above amount.
As per Section 50(3) a taxable person who makes an undue or excess claim of input tax credit shall pay interest on such undue or excess claim (utilized or not is irrelevant ), thus in our opinion interest would be chargeable.