Every society organized and operating or licensed under this article shall be, from the time of such organization, exempt from every state, county, and municipal tax, except real property taxes and unemployment compensation taxes; provided that nothing in this section shall be deemed to exempt the association or society from liability to withhold such taxes payable by its employees and pay the same to the proper collection officers, and to keep such records and make such returns and reports, as may be required in the case of other corporations, associations, or societies similarly exempt from the taxes hereinabove first mentioned; provided further, that the exemption hereby granted as to general excise taxes under chapter 237 shall not apply to any activity the primary purpose of which is to produce income.