Section 8B. Within sixty days after any meeting at which any amendment of the articles of organization has been adopted or within thirty days after any necessary approval by the department, whichever is later, articles of amendment, signed under the penalties of perjury by the president or any vice president and by the clerk or an assistant clerk, setting forth such amendment and the due adoption thereof, shall be submitted to the state secretary. The amendment shall become effective when the articles of amendment are filed in accordance with section six of chapter one hundred and fifty-six B, unless said articles specify, in accordance with the vote adopting the amendment, a later effective date not more than thirty days after such filing, in which event the amendment shall become effective on such later date. A signed copy of any amendment which relates to an increase or reduction of capital stock shall also be filed in the office of the department.