What is the difference between an oath and an affirmation in New York?

An oath is a solemn promise that invokes a higher power; an affirmation is the same promise made on the person’s own conscience, for anyone who declines to swear. In New York they carry identical legal weight. Either one exposes a liar to a perjury charge, so a notary treats them exactly alike.

The trap on the exam

Test takers assume an affirmation is a weaker, informal version that can’t support a perjury charge. Not so. The booklet makes an affirmation legally equivalent to an oath. If a signer objects to swearing on religious grounds, you offer an affirmation and it counts just as much.

A real example

A witness tells you she won’t swear an oath before signing her affidavit. You have her affirm, under the penalties of perjury, that her statement is true. She signs. If she lied, she can be prosecuted for perjury exactly as if she had sworn. The words changed; the legal force did not.

Remember it as Oath or affirmation, same weight, same perjury exposure.

What the law says

The booklet defines an affirmation as legally equivalent to an oath for those who conscientiously decline to swear, and defines “swear” to include every mode the law authorizes for administering an oath. A notary cannot administer either one to himself.

Source: NY DOS License Law, Definitions (pp. 19-21)

Walker's Notary is an independent study course. We are not affiliated with the New York Department of State. This answer traces to the current License Law publication; always confirm against the official source before you rely on it.