Late fee waiver for delayed GSTR-3B filings: limited post-due-date windows granted to specified classes of taxpayers. The state notification inserts a proviso waiving late fees for failure to furnish FORM GSTR-3B by the due date for specified classes of registered persons, defining for each class the relevant tax periods and a limited period after the due date during which late fees are waived: a fifteen-day waiver window for taxpayers above the aggregate turnover threshold for March and April 2021; a thirty-day window for taxpayers at or below the threshold liable under the primary return-filing requirement for March and April 2021; and a thirty-day window for below-threshold taxpayers liable under the proviso to the primary requirement for January-March 2021. The amendment is effective from the notified commencement date.