Updated return provision allows filing corrected income returns later, subject to exclusions and investigation-linked bars. A new sub section permits an updated return of income within twenty four months from the end of the relevant assessment year, in prescribed form and verification, but disallows updates that declare a loss, decrease tax liability, or increase refunds. Filing is barred where searches, surveys, seizures, requisitions, assessments, prosecutions, or communicated information under specified statutes or exchange agreements exist for the relevant year, or where the Board notifies classes of ineligible persons. Special rules allow conversion of previously filed loss returns into income returns and require corresponding updates for subsequent years where carryforwards or credits are affected; proof of tax payment is required under the Explanation.