Whether returns have to filed if the assesse has not effected any inward or outward supply during a tax period?

Section 39(8) of the CGST Act specifies that the periodical return in FORM GSTR-3 or FORM GSTR-4 (as the case may be) shall be furnished whether or not any supplies have been effected during the tax period. Here, it is relevant to note that the term “supplies” includes both inward and outward supplies.
However, a non-resident taxable person, an input service distributor, a person liable to deduct tax at source and person liable to collect tax at source would not be liable to furnish returns (in Forms GSTR-5, GSTR-6, GSTR-7 and GSTR-8, respectively) if they have not effected any supplies requiring them to furnish the respective forms (as mentioned above)

(ICAI FAQ PUBLICATIONS 06-09-2017 RETURNS : FAQ NO. 24)