(1) The Deputy Commissioner of Taxes may, at any time after expiry of the date specified in section 171, by a notice in writing, require a person to file a return of his income, if—

(a) such person is required to file his return under section 166; or

(b) the total income of such person is chargeable to tax in the relevant income year.

(2) The return under sub-section (1) shall be filed within such period, not being less than 21 (twenty-one) days, as may be specified in the notice or within such extended period as the Deputy Commissioner of Taxes may allow.