A written notice is required.
New York Labor Law Section 195 provides:
“Every employer shall:
6. notify any employee terminated from employment, in writing, of the exact date of such termination as well as the exact date of cancellation of employee benefits connected with such termination. In no case shall notice of such termination be provided more than five working days after the date of such termination. Failure to notify an employee of cancellation of accident or health insurance subjects an employer to an additional penalty pursuant to section two hundred seventeen of this chapter.”