Mass. Gen. Laws ch. 63 § 24A
Section twenty-one and the provision of section twenty-three imposing an excise in excess of two per cent of premiums taxable thereunder shall not apply to insurance companies organized in a state or country the laws of which do not impose retaliatory taxes or which grant, on a reciprocal basis, exemption from such retaliatory taxes to insurance companies organized in this commonwealth, or its agents. As used herein, "retaliatory taxes" means those taxes imposed upon insurance companies organized in another state or country which result from the fact that an insurance company organized in the taxing jurisdiction and doing business in such other state or country is taxable in an amount exceeding that imposed by the taxing jurisdiction upon an insurance company organized in such other state or country and doing business to the same extent in the taxing jurisdiction.
Mass. Gen. Laws ch. 63, § 24A