Mass. Gen. Laws ch. 184B § 4
The following discretionary powers, which shall be known as the "Statutory Principal Discretionary Powers", may be conferred by reference upon any fiduciary, and, unless otherwise provided in the instrument by which it is conferred, the term "primary beneficiary" in the statutory discretion shall mean each person currently entitled under the instrument to a share of income, or, if no person is currently entitled to income as of right or for priority of consideration, each person to whom income may currently be paid in the discretion of the fiduciary.
The fiduciary may at any time pay to or for the benefit of the primary beneficiary, the spouse of the primary beneficiary and children of the primary beneficiary under the age of twenty-five years such amounts of the principal held for the benefit of the primary beneficiary as the fiduciary deems advisable, giving reasonable consideration to other resources available to the distributee, for the comfort, maintenance, support or benefit of the distributee. The fiduciary may at any time pay to or for the benefit of other issue of the primary beneficiary and spouses and surviving spouses of issue of the primary beneficiary such amounts of the principal as the fiduciary deems necessary, after use of other resources available to the distributee so far as practicable without undue hardship, for the comfort, maintenance and support of the distributee and consistent with the best interests of the primary beneficiary and a due regard for the interests of all persons affected. Said discretion may be exercised even though the share of principal held for the primary beneficiary is thereby exhausted. Said discretion to pay principal to or for the benefit of any person includes the discretion after his death to pay or reimburse his estate for expenses incurred prior to his death and for reasonable funeral and burial expenses. If continuation of a trust or share has become impractical, the fiduciary may terminate it by distribution to the primary beneficiary or primary beneficiaries of the trust or share.
Principal, which in the exercise of such discretion is paid to or used for the benefit of any issue of the primary beneficiary or spouse or surviving spouse of such issue, shall be charged against any share of income or principal thereafter existing for such person or for any ancestor or issue of such person or for the spouse or surviving spouse of such person, ancestor or issue, unless the fiduciary upon equitable considerations shall otherwise determine. While the spouse or surviving spouse or surviving child of the testator or settlor is primary beneficiary of any trust or share which qualifies for a marital or orphan deduction under applicable federal tax laws, this discretion shall not apply to such trust or share except to permit the fiduciary to pay principal to or apply it for the benefit of such spouse or surviving spouse or surviving child, as the case may be. This discretion shall not be exercised in favor of any person then serving as such fiduciary who is otherwise eligible except for his maintenance or support nor in favor of his estate or his creditors or the creditors of his estate.
Mass. Gen. Laws ch. 184B, § 4