Quarterly return option for eligible small taxpayers; tax payable monthly and default filing frequency can be changed online. Notifies eligible registered persons with turnover within the specified threshold who opt for quarterly filing to furnish quarterly returns from the stated commencement, while requiring tax payment monthly; eligibility requires that the immediately preceding month's return was filed at the time of option, the option continues unless revised, and exceeding the turnover threshold during a quarter disqualifies quarterly filing from the next quarter. It also prescribes deemed options based on recent GSTR-1 filing and permits electronic revision of the default option on the common portal during the announced period.