Offer your thoughts or opinion on the input financial query or topic using your financial background.

The doctor didn't charge the health insurance in time, am I liable?
This has a straightforward answer. It's likely that your doctor and the hospital have no responsibility to ensure that your insurance claim is filed in a timely manner. They bill you whether you or they get reimbursed by insurance, or not. The insurance company is more than happy not to pay you any way they can. Sorry if this is harsh, but it's up to you to follow through. See also here.