Assessees must directly pay income tax if not deducted; non-compliance can lead to penalties under section 398(1).

Income tax must be paid directly by the assessee if there is no provision for deduction at the time of payment or if the tax has not been deducted as per the chapter's provisions. For income from specified securities or sweat equity shares from eligible start-ups, direct tax payment must occur within the specified timeframe. If a person required to deduct tax fails to do so, or fails to remit the deducted amount, and the assessee also fails to pay the tax, that person is deemed an assessee in default, subject to penalties under section 398(1).