This means the county where the Decedent lived and considered their primary home address before they died. Generally, you must file a New York State resident income tax return if you are a New York State resident and meet any of the following conditions.Why do I need a Certificate of Residence? Domicile for estate tax purposes means the place where a person has his or her permanent home. These forms and instructions are available in the General Clerk's Office, Room 108, in the Nassau County. That mechanism is the Certificate of Residence (COR). The COR is a specific-use document and may only be used for the above-mentioned purpose.