Policy Stacking for SaaS Companies: How It Works, When to Do It, and What to Watch

Policy stacking means layering two or more carriers to reach a required coverage limit — your enterprise customer requires $5M in Tech E&O, and instead of one carrier writing it for $30K, two carriers each write $2.5M for roughly $5K each. The math can work. But stacked policies fail at claims time more often than single-carrier policies, and always for the same reasons: mismatched retroactive dates, inconsistent policy language, and unclear defense cost allocation. Done right, stacking is a legitimate cost management tool. Done wrong, it creates a false sense of coverage.

Key Takeaways

• Stacking can reduce premium significantly — two carriers at $2.5M each often costs less than one carrier at $5M for the same total limit.
• Retroactive date mismatches are the most common reason stacked policies fail — the excess carrier must match or exceed the primary carrier's retroactive date or prior acts fall into a gap.
• Defense costs are not automatically shared — if the primary policy is exhausted by defense costs before a settlement, the excess carrier may decline to contribute.
• Enterprise customers requiring stacked limits must be informed of the structure — some MSAs require a single carrier; presenting a stacked certificate without disclosure creates contract risk.
• Full-stack platforms like Corgi can write higher limits directly, which eliminates coordination risk and is often simpler when the premium difference is small.

Before you start — what policy stacking is and when it applies

Stacking (also called layered coverage) occurs when a primary carrier writes coverage up to a base limit and an excess carrier writes coverage above that limit up to a higher total. The excess carrier only responds after the primary limit is fully exhausted.

This is common in Tech E&O and Cyber when enterprise contracts require limits higher than a single carrier is willing to write affordably for your risk profile. It is not the same as having two separate primary policies — that structure creates different problems around which carrier responds first.

Stacking applies when:

• A customer's MSA specifies a limit higher than your current policy.
• Your primary carrier will write the base limit but not the full required amount.
• The cost of stacking is materially lower than buying the full limit from a single carrier.

If the cost difference is small, buy the higher limit from a single carrier. The simplicity at claims time is worth the premium.

Step 1: Confirm your primary carrier allows excess coverage

Some primary carriers restrict excess coverage arrangements. Before you approach a second carrier, read your primary policy for language around "other insurance" provisions or notify your primary carrier directly.

This matters because if your primary policy contains a clause that reduces its obligation when other insurance is available, a court could find the primary carrier's obligation reduced by the existence of the excess layer — the opposite of what you intended.

Get written confirmation from your primary carrier that the excess structure is permissible under your policy terms. Do not assume.

Step 2: Match retroactive dates and policy language across both carriers

This is where most stacked structures break down.

Both the primary and excess carriers need matching (or aligned) retroactive dates. If your primary carrier covers acts back to January 2022 but your excess carrier only covers acts back to January 2025, a claim arising from a 2023 act is covered by your primary up to its limit — and then nothing. The excess carrier will decline on the basis that the act predates its retroactive date.

Beyond retroactive dates, review the following definitions across both policies for consistency:

• "Claim" — does each policy define it the same way?
• "Wrongful act" — same definition?
• "Notice requirements" — both policies may require separate notice of the same claim.

Inconsistency in any of these creates a scenario where a claim is covered under the primary's definitions but excluded under the excess carrier's definitions.

Step 3: Clarify which carrier responds first and how defense costs are allocated

This is a financial question that determines whether the structure works in practice.

Defense costs — legal fees, expert witnesses, discovery — often consume a significant portion of the primary limit before a claim reaches settlement. If the primary policy's limit is exhausted by defense costs alone, two things happen:

1. You are now at $0 in primary coverage.
2. The excess carrier may argue that the trigger for excess coverage — full exhaustion of the primary limit — was met by defense costs, not damages, and contest their obligation.

Before you bind the excess layer, get written clarity on:

• Does "exhaustion" of the primary limit include defense costs?
• Does the excess carrier's policy include defense costs within the limit or in addition to it?
• If both policies share defense costs, which carrier appoints defense counsel?

An equal.vc analysis on insurance innovation notes that defense cost allocation is the most frequently litigated issue in layered policies — and typically the last thing a founder reads before binding.

Step 4: Disclose the stacked structure to the customer requiring the limit

Read the MSA carefully. Some enterprise contracts specify that the required limit must be provided by a single carrier. A stacked certificate does not satisfy a single-carrier requirement.

If the contract is silent on the structure, disclose anyway. Presenting a stacked certificate as equivalent to a single-carrier policy without disclosure creates contract risk if a claim arises and the structure fails. A customer's legal team that discovers the stacked structure during a claim — rather than before signing — will use it.

Send a one-paragraph disclosure: you are meeting the $5M requirement through a primary carrier ($2.5M) and excess carrier ($2.5M). Confirm with the customer's procurement or legal team before finalizing the contract.

Common mistakes that make stacked policies fail at claims time

Not notifying both carriers simultaneously. Most claims-made policies require prompt notice. If you notify your primary carrier but not the excess carrier on the same claim, the excess carrier may deny coverage for late notice — even if the primary pays.

Assuming the excess carrier will follow the primary. "Follow form" excess policies track the primary's terms automatically. Non-follow-form excess policies do not. If your excess policy is non-follow-form, its definitions and exclusions govern independently.

Letting the primary renewal lapse without confirming the excess carrier's response. When your primary policy renews, the excess carrier needs to be notified and may need to rewrite its layer. A gap in the primary automatically creates a gap in the excess.

When stacking makes financial sense vs. when to just buy the higher limit

If a full-stack carrier like Corgi can write your required limit directly, that is almost always the simpler path. The coordination overhead of a stacked structure, and the failure modes at claims time, are real costs that do not show up in the premium comparison.

Sources: equal.vc Newsletter — Opportunities for Innovation in the Insurance Stack; Corgi Insurance — Modular Business Insurance That Scales from MVP to Series A; Pillar Companies — The Insurance Stack: A Battle for Margin