Updated return procedure under section 139(8A): ITR-U enables filing and verification to revise income within prescribed period. The amendment inserts Rule 12AC establishing the ITR-U as the mechanism for eligible taxpayers to furnish an updated return under section 139(8A), prescribing eligibility conditions, reasons for updating, filing modes (digital signature or electronic verification code), required form fields and computations for additional income, and vesting the Principal Director General/Director General of Income tax (Systems) with responsibility for procedures, formats, security, archival and retrieval standards for electronic submission and verification.