Investopedia explains Umbrella Insurance Policy

The premium for an umbrella insurance policy may be less expensive if the policy is purchased from the same insurer that provided the original auto, home or watercraft insurance. Depending on the provider, the policyholder who wants to add umbrella insurance policy is required to have a base insurance coverage of $150,000 to $250,000 for auto insurance and $250,000 to $300,000 for homeowners insurance.