Umbrella and excess liability. What it sits over matters more than how big it is.

Every umbrella or excess policy carries a schedule of underlying insurance, typically listing general liability, products and completed operations, employers liability, and commercial auto, each at a required primary limit. The layer extends only to what that schedule lists. If a line is missing from the schedule the umbrella does not respond to it, and if a primary limit falls below the scheduled requirement the layer may decline to drop down and fill the difference.

Generally no. An umbrella sits over general liability, products, auto, and employers liability. Professional liability or errors and omissions, directors and officers, cyber, and clinical trial liability each run their own towers, and excess capacity over them is bought and scheduled separately. This matters in life sciences because those excluded lines frequently carry the largest exposure.

The terms are used interchangeably in the market but describe different things. Excess liability simply adds limit above a primary policy on the same terms. An umbrella can be broader, and may drop down to respond where an underlying policy does not cover a loss at all, subject to a self-insured retention. The practical difference shows up in what the layer will do when the primary does not respond, which is why the actual wording matters more than the label.

The number is usually set by contracts rather than by revenue. Sponsor MSAs, hospital and GPO vendor agreements, and distribution contracts state required combined limits, and the umbrella is what bridges the gap between the primary lines and that figure. Sizing should start from the most demanding contract in the stack, with the products and completed operations exposure as the second input.

Not reliably. Manuscript or broadened wording added to a primary policy does not automatically transfer to a following-form excess layer. This is worth verifying any time the primary has been amended, including for coverage territory, because a broadened territory on the primary achieves little if the layers above it follow narrower wording.