Section 13(4) in The Adjudicating Authority (Procedure) Regulations, 2013
(4)If for any reason the such summon or notice can not be served personally, the complainant or applicant may serve the same by affixing a copy of the summon on the outer door or some other conspicuous part of the house or office in which the defendant/ respondent resides or carries on business or personally works for gain, and shall then return the original to the Registrar or Administrative Officer, with a report endorsed thereon or annexed thereto stating that he has so affixed the copy, the circumstances under which he did so and the name and address of the person, if any, in whose presence the copy was affixed and the Authority issuing the summon or notice shall in that event declare that the summon has been duly served on the defendants or respondents.
