New York Codes, Rules and Regulations
Title 15 - Department of Motor Vehicles
Chapter I - REGULATIONS OF THE COMMISSIONER
Subchapter B - Registration, Certificate of Title, and Number Plates
Part 24 - Registration Of Motor Vehicles Of Severely Disabled Persons
Section 24.4 - Proof of severe disability

(a) Upon an original registration issued on or after April 1, 1981, or upon the renewal of a registration, the original of which was issued prior to April 1, 1981, proof of severe disability will be required and may be required upon subsequent renewals. Such proof shall consist of a letter signed by a physician on his letterhead (if licensed outside of this State, must include state of licensure and license or certification number), or of a statement from the Commissioner for the Blind and Visually Handicapped, or a certification from the Office of Vocational Rehabilitation, or from a hospital, clinic or medical facility. A copy of the letter or statement is acceptable as is a copy of a physician's letter submitted to obtain a New York State Handicapped Parking Permit or a New York City Special Vehicle Identification Permit. The letter or statement shall have been issued within the preceding year, except at the discretion of the district director or county clerk. The letter, certification or statement must certify that the applicant has one or more of the permanent disabilities or conditions listed in section 24.2 of this Part.

(b) A permanent special vehicle identification parking permit issued pursuant to section 1203-a of the Vehicle and Traffic Law shall be considered acceptable proof of severe disability.