Form a corporation, limited liability company (LLCs), limited partnership or more and do business in New York State. A "Sole Proprietorship" or "General Partnership" seeking to operate in the County of Middlesex must file a Certificate of Trade Name with the County Clerk.Free viewers are required for some of the attached documents. Organizations seeking exemption from Sales and Use Tax must complete all steps of this application. A new corporate tax applies to corporations and banks, other than federal S-corporations, that do business in New York City.