Umbrella and Excess Liability Insurance

Umbrella vs. Excess Coverage

Umbrella and excess liability insurance provide additional limits above underlying primary policies. An excess policy follows the terms and conditions of the underlying policy, providing additional capacity in the same coverage form. An umbrella policy may also broaden coverage, filling gaps between underlying policies and covering certain exposures not addressed by primary coverage (subject to a self-insured retention). Both types sit above primary general liability, auto liability, and employers liability policies, providing the insured with higher overall limits of protection against catastrophic liability events.

Pricing Excess Layers

Pricing excess layers requires modeling the severity distribution of claims in the layer between the attachment point and the policy limit. Increased limits factors (ILFs) express the expected loss in each layer relative to a basic limit. Actuaries derive ILFs from large claim data using severity distributions (lognormal, Pareto, or mixed distributions) fitted to observed claim sizes. The shape of the severity distribution above the attachment point is critical and often uncertain due to limited data in the tail. Loss development in excess layers is typically longer and more volatile than in primary layers, as large claims take longer to settle. Clash covers, which respond when a single occurrence triggers claims under multiple primary policies, require special modeling of multi-claimant scenarios.