Return filing deadline for FORM GSTR-3B set with staggered due dates and mandatory electronic ledger payments. Specification of due dates for filing FORM GSTR-3B for October 2020 to March 2021 requires electronic submission through the common portal by the twentieth day of the succeeding month, with a later date for taxpayers below a prescribed turnover threshold. Registered persons filing FORM GSTR-3B must discharge tax by debiting the electronic cash or credit ledger as applicable, and pay interest, penalty, fees or other amounts by debiting the electronic cash ledger, not later than the last date for furnishing the return.