Defective return conditions govern incomplete filings, missing audit reports, and mismatched MAT or AMT carry-forward claims. A return of income is treated as a defective return where the prescribed fields, parts, schedules, statements, or columns are not duly completed, including particulars for computation of income, gross total income, and total income. Defect status also arises where the audit report is not furnished before filing in auditable cases, where required tax payment details are not duly filled in, or where claimed MAT or AMT credit is inconsistent with the latest allowed carry forward position. The Board may notify classes of persons to whom these conditions do not apply, or apply with modifications.