GSTR-3B filing deadline set for monthly returns; taxes must be paid via electronic cash or credit ledgers by that due date. Due date for furnishing FORM GSTR-3B for April-June 2019 is the twentieth day of the month succeeding each tax period, effective from 7 March 2019. Registered persons must discharge tax, interest, penalty, fees or other amounts by debiting the electronic cash ledger or electronic credit ledger, as applicable, not later than that due date, subject to statutory payment provisions.