The unlimited-discretion split is the whole architecture. Under New York's statute, an authorized trustee with unlimited discretion to invade principal may appoint part or all of it to a new trust for, and only for, one, more than one or all of the current beneficiaries of the invaded trust, and may exclude any of them. The successor and remainder beneficiaries of the new trust may likewise be some or all of those of the old one. A trustee with a power to invade but without unlimited discretion may still decant, but the new trust must keep the same current beneficiaries, the same successor and remainder beneficiaries, and the same language authorizing distributions of income and invasions of principal. The second version is a tool for fixing administration and structure; the first can genuinely redraw who benefits and by how much.
"Unlimited discretion" is defined, and more generously than the phrase sounds: it means "the unlimited right to distribute principal that is not modified in any manner," and the statute adds that words such as best interests, welfare, comfort or happiness are not treated as modifying it. A power limited to health, education, maintenance and support is a different matter, and falls on the narrower side.
What the trustee may and may not build into the new trust. The term of the appointed trust may run longer than the invaded trust's, including for a current beneficiary's lifetime, and where a limited-discretion trustee extends the term, the statute allows unlimited discretion to invade principal during the extended period. A trustee exercising the broader power may grant a beneficiary a discretionary power of appointment in the new trust, but only where that beneficiary could have received the principal outright under the invaded trust, and the permissible appointees may be narrowed only in specified ways. The exercise is itself treated as the exercise of a special power of appointment.
Five things a decanting may not do. It may not reduce, limit or modify a beneficiary's mandatory right to income or principal, a mandatory fixed-dollar or unitrust payment, or a right to withdraw a percentage or a stated dollar amount, once that right has come into effect. It may not reduce or indemnify a trustee's liability or excuse a failure to exercise reasonable care. It may not strip out a provision letting someone else remove or replace the trustee doing the decanting, unless a court says otherwise. It may not conclusively fix the value of an asset. And it may not jeopardize a deduction or exclusion originally claimed for a contribution to the invaded trust, including the annual exclusion, the marital deduction and the charitable deduction, nor the qualification of a transfer as a direct skip, nor any other specific tax benefit a contribution originally qualified for. A separate paragraph requires the trustee to consider the tax implications of the exercise.
One carve-out inside the first prohibition matters a great deal. Despite the bar on reducing a mandatory distribution right, the statute expressly allows an appointment to a supplemental needs trust conforming to the state's own provision. That is the case decanting is most often reached for: a beneficiary's circumstances change, a mandatory payment now disqualifies them from means-tested benefits, and the trust as drafted cannot stop paying.
The duty, and the limit the duty imposes. A trustee exercising the power has a fiduciary duty to act in the best interests of one or more proper objects of the power and as a prudent person would in the circumstances. The trustee may not exercise it where there is substantial evidence of a contrary intent on the creator's part, unless it can be established that the creator would likely have changed that intention in the circumstances now existing. The statute adds a clarification worth noticing: the provisions of the invaded trust are not by themselves substantial evidence of a contrary intent, unless the trust expressly prohibits the exercise. A general prohibition on amendment, or a spendthrift clause, does not block it.
The procedure is administrative rather than judicial. The exercise is evidenced by a written instrument, signed, dated and acknowledged by the trustee. It takes effect 30 days after the instrument is served on the people entitled to notice, unless they consent in writing to an earlier date, and it is irrevocable from then. No consent from the creator or the beneficiaries is required, and no court approval, though the trustee may seek approval if it wants the comfort. Copies go to the living creator, to anyone with the right to remove or replace the trustee, and to the persons interested in both trusts. An interested person may serve a written objection before the effective date, though failing to object is not consent, and nobody loses the right to compel an accounting.