under reported tax liability

jeevan lingayat (manager) (214 Points)

01 March 2019  
Dear Taxpayer, you have under reported tax liability in GSTR-3B as compared to GSTR-1 by more than Rs. 1.00 lakh for Oct-Dec 2018. Please take corrective action.

Please inform what does it means? Recd to mob number which is not registered. our return periodicity is monthly.