Form a corporation, limited liability company (LLCs), limited partnership or more and do business in New York State. You will need to fill out Form SS-4, the application for employer identification number.This form is for general instructions that apply to all corporation tax forms. It includes a variety of topics about how to fill out your form. Anyone who will operate a business in Suffolk County under a name, other than his or her own, must file a Business Certificate with the County Clerk's Office. Corporations are required to have an attorney in all proceedings (except Small Claims or Commercial Small Claims). We're here to answer all your questions. Fill out our contact form and we'll connect you with the people who can help. Applications for third-party notifications must be filed with the tax collecting officer no later than the 1st of October. Exemptions. Challenge examinations are not available for all courses.