New York State Registration Requirements
In order to do business in New York City, you must also register your company with the State of New York. Partnerships must register with the County Clerk's Office where the business is located. If you plan to conduct a sole proprietorship under a name other than your own, such as a trade name or an assumed name (referred to as D.B.A., or "doing business as"), you must register that name with the County Clerk's Office where the business is located. Corporations must register with the Secretary of State, Department of State, in Albany

To Apply for a Federal Employer ID Number (EIN)
According to federal law, corporations, partnerships, and certain sole proprietorships must have an Employer Identification Number, or EIN, to use as a taxpayer identification number. To do business in New York City, the EIN assigned by the IRS is sufficient. No additional identifying number is required.

Sole proprietors need this number only if they pay wages to one or more employees, or if they are required to file any federal pension or excise tax returns. Otherwise, sole proprietors can use their Social Security Number as a taxpayer identification number.

Internal Revenue Service (IRS.gov)
To apply for an Employer Identification Number, use Federal Form SS-4.