If you wish to incorporate, this must be processed through the Department of State in Albany, the form required is a T-339. Form a corporation, limited liability company (LLCs), limited partnership or more and do business in New York State.These instructions are for use with the Suffolk District Court COMPLAINT FORM (DC-283). Page version of this information is available at the courthouses. How do I register a business in Suffolk County? Contact the Suffolk County Clerk located in Riverhead at (631) 852-2000.