What revision! There is only one option. Add the missed purchase turnover to this year's purchase and file it. There is no such area like amending last year's sales and purchase in the current year GSTR4. My solution is this-email the missed purchase with full details to the GST authority under my jurisdiction as the prime step. And then add the missed purchase turnover in 2021-22 GSTR4. There should be a segment in GSTR4 liviz PREVIOUS TAX PERIOD AMENDMENTS.