Waiver of late fee for delayed GSTR-3B returns, with an extended retrospective filing window for affected taxpayers. The notification, issued under section 128 of the Uttar Pradesh GST Act, waives portions of late fees for registered persons who failed to furnish FORM GSTR-3B returns from July 2017 onwards, setting reduced excess-per-day thresholds where central tax payable is nil and fully waiving late fees for persons who file returns for July 2017 to September 2018 within a specified retrospective filing window; it supersedes earlier notifications except as to prior actions or omissions.