REGARDING LAPSED ITC

Hai gd mng to caclubindia team, 

          I am D. Srinivasulu, cleartax customer. Actually my client got problem, working as contractor, his liability in in 08/2018 is around 592000/-after set off itc 235000/-we cannot filed Gstr 3B 08/2018 due  some problems. That's why all gstr 3b returns pending from 08/2018 to till  date. But Gstr 1 filed up to I think 03/2020.the officer issued notice to pay liability for 08/2018.here the officer said that you have to pay tax without adjust itc I. E. 235000/- because this is lapsed due not filing gstr 3b returns more than 2 years I. E. From 08/2018 to till date. So total liablity is 592000+235000=827000+plus penalty of 827000/-first of all lapsed itc 235000/- correct or not. Next levie penalty . Please suggest