GSTR-3B filing deadlines set monthly; returns and tax payments must be filed and discharged via electronic ledgers. Specifies filing of FORM GSTR-3B for January, February and March 2018 electronically through the common portal by the listed last dates (20th of the succeeding month for each month). Requires every registered person furnishing FORM GSTR-3B to discharge tax, interest, penalty, fees or other amounts payable by debiting the electronic cash ledger or electronic credit ledger, as applicable, not later than the corresponding last date for filing the return, subject to the statutory provisions.