Which provision of the Income-tax Act, 2025 deals with defective income-tax returns?

Section 263(7) provides that a return not conforming to the prescribed conditions is defective; the Assessing Officer may intimate the defect and allow fifteen days, or a longer period on application, to rectify it, failing which the return is invalid. Section 263(4) covers belated returns, section 263(5) revised returns and section 264 the tax return preparer scheme.