GSTR-3B filing deadlines require electronic return submission and discharge of liabilities via cash or credit ledgers by due dates. The notification prescribes that returns in FORM GSTR-3B for the months specified shall be furnished electronically through the common portal by the stated last dates, and requires every registered person furnishing FORM GSTR-3B to discharge tax, interest, penalty, fee or any other payable amount by debiting the electronic cash ledger or electronic credit ledger, as applicable, not later than the last date for furnishing the return.