Regarding Interest on Gst liability

Namasker and Good Morning to all Experts
Just want to ask simple query
Gross liability = 100
Input tax credit = 50
Net liability. = 50
Supposed we deposit tax liability 4 daya late . than interest will be paid by 4 days @ 18℅.
Now please tell me that in which amount I will paid interest my gross liability or net liability ie 50