New York Codes, Rules and Regulations
Title 10 - DEPARTMENT OF HEALTH
Chapter VI - State Emergency Medical Services Code
Part 800 - Emergency Medical Services
Emergency Medical Services Personnel
Section 800.14 - Emergency medical technicians certified by states bordering new york

Emergency medical technicians certified by Vermont, Massachusetts, Connecticut, New Jersey, or Pennsylvania may practice in New York State without New York State certification, while (a) transferring a patient across the border between New York State and the certifying state or (b) providing emergency medical care in New York State pursuant to a mutual aid agreement with a New York State-certified or registered ambulance service. The mutual aid agreement must be in writing, signed by an authorized officer of both services, and must delineate the protocols to be adhered to by the out-of-state emergency medical technicians and shall be on file with the department.