If the accident is not my fault, do I still have to tell my insurer? How will this impact my coverage and premiums?

Yes, you still need to report your accident to your insurance company. Because New York is a no-fault state for automobile accidents, your insurance company is required to pay for your medical expenses and lost earnings up to a certain amount. That amount will vary depending on the insurance policy you hold. In addition, to the extent you might be, at least, partly at fault, you must notify your insurance company right away in the event the other party brings a claim against you.