Dividends included therein shall be deducted other than dividends from or on account of the ownership of shares in a corporate trust, as defined in section one of chapter sixty-two, engaged in business in the commonwealth, or deemed distributions and actual distributions, except actual distributions out of previously taxed income, from a DISC which is not a wholly owned DISC, or any class of stock if the insurer owns less than fifteen per cent of the voting stock of the corporation paying such dividend.
Mass. Gen. Laws ch. 63, § 22B