Defective return procedures allow notice and short-period rectification opportunity, else return treated as invalid for assessment. Where the Income-tax Officer considers a return defective, he may notify the assessee and allow a limited period to rectify; failure to rectify within that period or any discretionary extension results in the return being treated as invalid and the provisions applicable to non-filing will apply, although the officer may condone delay if rectification occurs before assessment. A return is defective unless prescribed annexures, tax computation statement, proofs of tax payments and compulsory deposits, required accounts or audited documents or, where no books are kept, a specified statement of turnover and balances are furnished.