Is there a deductible for commercial umbrella insurance?

Usually, there is no deductible.

Umbrella policies typically don’t have a deductible; instead, they require your primary policy to cover its limits before the umbrella coverage applies.

A liability claim exceeded the primary policy limit of $1 million. The umbrella policy immediately covered the excess without a deductible.

Verify with your provider whether your umbrella policy has a self-insured retention (similar to a deductible).