§ 638. New York source income of a part-year resident. (a)
Individuals. The New York source income of a part-year resident
individual shall be the sum of the following:

(1) New York adjusted gross income for the period of residence,
determined in accordance with part II of this article as if the
taxpayer's taxable year for federal income tax purposes were limited to
the period of residence.

(2) New York source income for the period of nonresidence, determined
in accordance with section six hundred thirty-one as if the taxpayer's
taxable year for federal income tax purposes were limited to the period
of nonresidence.

(b) Trusts. The New York source income of a part-year resident trust
shall be the sum of the following:

(1) New York adjusted gross income for the period of residence,
determined in accordance with paragraph four of subsection (e) of
section six hundred one as if its taxable year for federal income tax
purposes were limited to the period of residence.

(2) New York source income for the period of nonresidence, determined
in accordance with section six hundred thirty-three as if its taxable
year for federal income tax purposes were limited to the period of
nonresidence.

(c) Stock option grants, stock appreciation rights and restricted
stock. A part-year resident taxpayer who has been granted statutory
stock options, restricted stock, nonstatutory stock options or stock
appreciation rights and who, during such grant period, performs services
within New York for, or is employed within New York by, the corporation
granting such option, stock or right, shall compute his or her New York
source income as determined under rules and regulations prescribed by
the commissioner.