We have a new physician who is not yet credentialed on many managed care plans. Our office is billing his claims under my name. Is this legal?

No, it is not legal to bill for one physician's services under the name of another physician. This practice constitutes a false claim and probably violates your payer contracts as well. Meet with your office manager, administrator, and/or business manager immediately and get the practice stopped.

You may also want to place calls to your malpractice carrier to have them walk you through controlling any liability that this exposed you to. Ask the carrier its advice on whether and how you should tell insurance companies, and what steps you should take to protect yourself.

Meanwhile, document everything you do about this situation. And if this was intentional (versus an administrative mistake), then you may want to evaluate the environment in which you're practicing.