A 17yr old and 16 yr old can legally have sex in ny state. The Law is 21 and over and under 17. For under 21 its 15. 16 if 20. it can not be more than 4 years. Just letting you know the official law on ny state website.

There is an "affirmative defense" clause in the law based on a 4 year age difference; however, it should not be interpreted as an automatic free ticket from criminal prosecution.

In New York Penal Code (Criminal laws for the state) a violation of the sex offense laws takes place when a perpetrator commits specific acts against a victim without their consent.

Lack of consent is defined within the New York Criminal code Article 130.05 in detail that includes forcible compulsion, physical helplessness, and age of consent.

Age of consent is defined this way. A person is incapable of consenting to sexual intercourse or sexual contact if they are less than 17 years old.

A person 18 years of age or more can be charged with a 1st degree sexual offense if the victim is under the age of 13. 1st degree crimes are the most serious violations.

A person 18 years of age or more can be charged with a 2nd degree sexual offense if the victim is under 15 years of age; however, if the perpetrator is less than 4 years older than the victim, this “may” be used in an affirmative defense where evidence is introduced to negate criminal liability.

Sources:
Laws of New York
New York City Alliance Against Sexual Assault