Interest on Gst liabilty

Amit Mohan Pandey (Practising chartered accountant)   (371 Points)

21 February 2019  
I have pending liability of 500000 to be paid in 2017.. also i have excess input amount of 400000 from 2017 to till date.So my question is do i have to pay interest on 500000 or 100000 (500000-400000).

i have showed liability in gstr 1 of 2017 but forget to show in gstr3b of 2017.
pls advice and also quote section number- or circular if any..