N.Y. Comp. Codes R. & Regs. tit. 20, § 121.1
(2) The fiduciary of a trust, which makes the accumulation distribution within the meaning of this Part, must file, with the New York State fiduciary return (form IT-205) for the taxable year of the trust in which such accumulation distribution is made, the following:
(iv) a statement showing the share of each beneficiary in
(d) the excess tax paid by the trust for each prior year as determined under subparagraph (iii) of this paragraph.
(f) Meaning of terms.
As used in this Part, the term resident beneficiary includes a resident individual, estate or trust.
Tax Law, § 621(a)
(a) General.
A resident beneficiary of a trust, whose New York adjusted gross income includes all or part of an accumulation distribution, as defined in section 665 of the Internal Revenue Code, is entitled to a credit determined under this Part against the New York State personal income tax otherwise due from the resident beneficiary for the taxable year. The amount of the credit is the portion of the excess tax, as defined in subdivision (b) of this section, paid by the trust making the accumulation distribution for each prior taxable year affected by the accumulation distribution which is attributable to the amount included in the resident beneficiary's New York adjusted gross income for the taxable year with respect to the accumulation distribution and any New York fiduciary adjustment applicable; see subdivision (c) of this section. See section 121.2 of this Part for limitations on the amount of accumulation distribution credit which may be claimed under this Part.
(b) Excess tax.
The excess tax must be determined in accordance with the provisions of this subdivision. For purposes of this Part, the term excess tax means any amount of New York State personal income tax paid by the trust for a prior taxable year which would not have been payable if the trust: (1) had made a distribution to beneficiaries in the amount deemed to have been distributed during such prior taxable year under section 666 of the Internal Revenue Code; (2) had allocated to the beneficiary the beneficiary's share of the redetermined New York fiduciary adjustment by reason of the accumulation distribution; and (3) had eliminated from the recomputed New York taxable income of the trust that portion of the amount of any of the New York modifications relating to amounts allocated to principal which are no longer includible in the New York taxable income of such trust by reason of the accumulation distribution.
(c) New York fiduciary adjustment.
For purposes of this Part, the respective shares of a resident trust and its beneficiaries in the New York fiduciary adjustment as determined under Part 119 of this Article must be redetermined, for any year affected by an accumulation distribution, to take into account the amounts of Federal distributable net income deemed to have been distributed in said year by reason of the accumulation distribution.
(d) Other provisions.
No credit under this Part is allowed with respect to any amount for which a modification is allowable under section 112.3(e)(3) of this Article. Credit under this Part is allowable only to the extent that the accumulation distribution is included in New York adjusted gross income of the resident beneficiary.
(e) Method of claiming credit.