Revision of income tax return allowed until shortly before assessment-year end or before assessment completion. A taxpayer may file a revised return to correct mistakes, omissions or wrong statements, but only within the prescribed time limit: not later than three months before the end of the assessment year or before completion of assessment proceedings, whichever is earlier. Returns originally filed in paper/manual form generally cannot be revised electronically; where revision by electronic means is available, it is filed under the statutory revision mechanism.