Reports or returns or other matter which are required by law to be verified by oath or affirmation and filed with the Tax Commission may be verified by oath or affirmation taken before a person authorized to administer oaths, or by a declaration in writing that the report or return or other matter is signed under the penalties of perjury. The fact that a report or return or other matter purports to have been signed by a person shall for all purposes be prima facie evidence that he in fact signed the report or return or other matter.