Most umbrella carriers require to to carry a minimum amount of liability coverage on your vehicles, home, etc...when most people think "minimum" with regard to insurance, they think of the minimum required by law. That's not what it means in context to an umbrella policy. A safe bet is that an umbrella carrier will require you to carry at least 100/300/100 on your vehicle, and at least $250k on your home, before you can get an umbrella policy. So, if you want an umbrella policy, and you're carrying more liability coverage than they require, can you reduce down to the minimum amount they require? Yes. Should you? That depends.