Provided further that such condition shall apply cumulatively for the period April and May, 2021 and the return in FORM GSTR-3B for the tax period May, 2021 shall be furnished with the cumulative adjustment of input tax credit for the said months in accordance with the condition above Provided that a registered person may furnish such details, for the month of April, 2021, using IFF from the 1st day of May, 2021 till the 28th day of May, 2021. This Notification has come into effect from 1st day of May, 2021.