Notice issued U/S 142(1)(i)

Dear Sir, I have been issued notice u/s 142(1)(i) which is as under; "In connection with assessment for assessment year 2017-18, you are required to prepare a true and correct return of your income in respect of which you are assessable under the Income-tax Act, 1961 (Act), during the previous year relevant to the assessment year, mentioned above. The said return of income should be in appropriate form as prescribed in Rule 12 of the Income Tax Rules, 1962 and duly verified in accordance with provisions of section 140 of the Act. The said return of income is required to be furnished as per the conditions and manner prescribed in Rule 12 of Income-tax Rules, 1962, on or before 27/01/2018." Now my question to above is, What documents I need to give for justifying above notice and do i also need to file ITR again in response to notice served u/s 142(1) as above? My client doesn't maintain books of account since his turnover is less than 1 CR. PLEASE GIVE ME GUIDANCE Thanks & Regards NIshant Shah