What situations does an umbrella policy actually cover that my home and auto policies don't?

An umbrella extends your existing liability limits and also broadens what's covered. Beyond big auto and home injury claims, it typically adds protection for things standard policies exclude or limit: libel, slander, defamation, false arrest, and landlord liability if you rent out property. It covers claims that pierce your underlying limits, then keeps paying up to the umbrella's own limit.

What it does not cover is your own injuries or property, intentional acts, or business and professional liability, which need separate commercial or malpractice coverage. Think of it as broad personal-liability protection for catastrophic and unusual claims. Match the umbrella limit roughly to your net worth plus a cushion for future income, since a judgment can reach assets you haven't earned yet.