N.Y. Comp. Codes R. & Regs. tit. 20, § 4-4.3
(b) Commissions received by a taxpayer are allocated to New York State if the services for which the commissions were paid were performed in New York State. If the services for which the commissions were paid were performed for the taxpayer by salesmen attached to or working out of a New York State office of the taxpayer, the services will be deemed to have been performed in New York State.
Example 2:
A taxpayer is a New York State sales agent of a Pennsylvania manufacturer. A salesman working out of the New York State office of the taxpayer received an order in New Jersey. The order was forwarded to the Pennsylvania manufacturer which accepted it, filled it and shipped it direct to the customer. The taxpayer's commission is allocated to New York State.
(c) For rules for allocating receipts of registered securities or commodities brokers or dealers, see section 210.3(a)(9) of the Tax Law and section 4-4.7 of this Subpart.
(d)
Tax Law, § 210(3)(a)(2)(B) and (6)