Right to file revised return: no prior permission required and permission-application cannot substitute for revision.
No prior permission is required to file a revised return; the assessee has a right to submit a revised return. An application framed as seeking permission to revise the originally filed return cannot be treated as, or substitute for, a valid revised return, and therefore does not meet the statutory mechanism for revision.

Revised return can be filed multiple times within the limitation period when omissions or errors are discovered in the original filing.
An assessee may file a revised return multiple times so long as each revision is within the applicable limitation period and corrects an omission or wrong statement discovered in the earlier return, permitting successive amendments prior to expiry of the statutory time bar.

Revised return substitutes the original return, while mere corrections leave the original filing intact for assessment.
A validly filed revised return withdraws and substitutes the original return for assessment purposes; corrections or amendments made to a filed return without filing a revised return do not change the filing's character and therefore do not effect such substitution.

Auditor's report: may be filed with a revised return to rectify omission from the original tax return.
Where an assessee obliged to furnish an auditor's report with its income tax return fails to submit it with the original filing, the auditor's report may be furnished subsequently with the revised return, permitting rectification of that omission under the return amendment regime.

Assessment under section 143(1) not an assessment; revised return filed after intimation remains valid for consideration.
An intimation issued under section 143(1) is procedural and does not constitute a formal assessment; therefore a revised return filed after such an intimation but within the statutory period must be treated as duly filed and considered by the Assessing Officer.