Section 621. Credit to trust beneficiary receiving accumulation distribution

(a) General. A resident beneficiary of a trust whose  New  York  adjusted  gross  income  includes  all  or part of an accumulation
  distribution by such trust, as defined in section six hundred sixty-five
  of the internal revenue code, shall be allowed a credit against the  tax
  otherwise  due under this article for all or a proportionate part of any
  tax paid by the trust under this article or  under  article  sixteen  of
  this  chapter  (as  such  article  was  in  effect on or before December
  thirtieth, nineteen hundred sixty), for any preceding taxable year which
  would not have been payable if the trust had in fact made  distributions
  to  its  beneficiaries  at  the  times  and  in the amounts specified in
  section six hundred sixty-six of the internal revenue code.
    (b) Limitation. The credit under this section shall not reduce the tax
  otherwise due from the beneficiary under this article to an amount  less
  than  would  have  been due if the accumulation distribution or his part
  thereof were excluded from his New York adjusted gross income.