What You Need to Know About E&S Policy Endorsements

Written by E. Stuart Powell, Jr., Insurance and Risk Management Consultant.

Excess and surplus (E&S) lines commercial insurance policies are built for flexibility, and that flexibility shows up most clearly in their endorsements. Unlike admitted carriers—who must file and standardize their forms - E&S insurers can tailor coverage with a wide range of standard and non‑standard endorsements that reshape the basic policy form in meaningful ways.

🏗️ Why E&S Policies Rely So Heavily on Endorsements

E&S carriers operate outside the traditional rate-and-form filing requirements. That freedom allows them to insure unusual, high‑risk, or emerging exposures that don’t fit neatly into ISO‑based admitted policies. Because these risks vary widely, endorsements become the primary tool for customizing:

• Coverage scope
• Terms and conditions
• Exclusions and limitations
• Reporting or compliance requirements
• Risk‑specific obligations for the insured

In other words, the base form is just the starting point. The policy's real architecture is built through endorsements.

🧩 Standard vs. Non‑Standard Endorsements

E&S carriers often use two broad categories of endorsements:

1. Standard Endorsements

These are commonly used across many policies and may resemble ISO‑style modifications, such as:

• Additional insured endorsements
• Waiver of subrogation
• Primary and noncontributory wording
• Designated premises limitations
• Professional services exclusions

Even though they’re “standard,” they can still significantly alter coverage - especially when they narrow or condition the insuring agreement.

2. Non‑Standard or Manuscript Endorsements

This is where E&S underwriting really shows its creativity. Manuscript endorsements are drafted specifically for a particular risk, industry, or insured. They may:

• Add coverage for unique operations
• Modify exclusions to fit the insured’s business model
• Create entirely new conditions or reporting requirements
• Tailor deductibles, retentions, or sublimits
• Address emerging risks (e.g., cannabis, cyber‑physical exposures, new construction methods)

Because these endorsements are not standardized, they require careful reading. A single manuscript clause can dramatically expand or restrict coverage. One recent example, reported by an agent, involved a general liability policy containing a non‑standard Premium Audit endorsement. The endorsement stated that if the audited earned premium is less than the advance or deposit premium, the advance or deposit premium becomes the minimum premium.

This creates an asymmetrical audit process. If the audited earned premium exceeds the advance or deposit premium, the policyholder must pay the additional premium. However, if the audited earned premium is less than the advance or deposit premium, the advance or deposit premium is treated as the minimum policy premium, and the difference is not returned to the policyholder.

🔍 The Practical Impact

For brokers, risk managers, and insureds, endorsements in E&S policies are not “fine print” - they are the policy. They can:

• Override the base form
• Introduce new obligations
• Change how claims are adjusted
• Add or remove entire coverage sections
• Shift risk back to the insured if misunderstood

This is why E&S policies demand a review of endorsements, especially any non-standard endorsements. Two policies with the same declarations page and basic coverage form can function very differently once endorsements are applied.

or unconventional risks, but their flexibility places greater responsibility on both agents and insureds. Endorsements - whether standard or manuscript - ultimately define the scope of coverage, making it essential to understand how they modify the base policy for risk assessment, compliance, and claims preparedness.

Agents have long been advised to tell policyholders - and to document that they have done so - to “read your policies.” This guidance is especially important with E&S policies. Agents should also explain that E&S policies may differ in some important ways from policies issued by standard‑market insurers, where the needed coverage or limits of coverage may not be available.

Because most agent training is based on ISO-standard policy forms, agents should carefully review any E&S policy for non‑ISO endorsements. When non‑standard endorsements appear, agents should request an explanation from the broker and document that request. Whether or not the broker provides a substantive explanation, documenting the inquiry remains valuable.

Strictly speaking, only the insurer and legal counsel can interpret the insurance contract with authority. Nonetheless, clients expect agents to understand how coverage is intended to function. Agents may comment on the policy's general purpose, but they should also educate clients that the insurer will ultimately determine how the policy applies to a specific claim or set of circumstances.