Composition scheme extension permits late electronic opt in and mandates cumulative input tax credit adjustment in a subsequent return. Allows late opt in to the composition scheme for 2020 21 by requiring registered persons to electronically file an intimation on the common portal, duly signed or verified, by the extended deadline and to furnish the prescribed ITC statement by the extended filing date. Requires cumulative application of the input tax credit adjustment condition across the listed months and mandates that the subsequent periodic return include a single cumulative adjustment of input tax credit as per that condition.