A New York tax preparer must have a New York tax preparer registration identification number (NYTPRIN) or qualify for an exclusion from the requirement. Either the NYTPRIN or the NY exclusion code must be entered  when file a NY return on the information worksheet. Information about NY preparer registration is available from the New York State Department of Taxation and Finance web site New York State Tax Preparer Registration.

If you are paid to prepare less than 10 NYS returns you do not have to pay the $100 commercial preparer fee. If you are paid to prepare at least one NYS return you need to register for the NYTPRIN. 

The NYS tax form asks for your NYTPRIN even if you are filing as a non-paid preparer. Without that number it will generate an error and not efile.