Claims-Made vs. Occurrence Insurance: Key Differences Explained

Claims-made vs. occurrence insurance explained: how each form works, when tail coverage is needed, and which policies use which form.

A contractor files a claim fully expecting coverage. The incident happened during the policy period. The investigation happened during the policy period. The denial letter arrives anyway, because the policy had already lapsed when the claim was filed, and it was written on a claims-made form. One distinction the contractor never thought about until that moment determined the entire outcome.

Claims-made and occurrence policies look similar on paper. Both cover liability. Both require premiums. Both show up on a certificate of insurance. What separates them is when coverage actually activates. For an occurrence policy, the incident date drives everything. For a claims-made policy, the date the claim gets filed against you is what determines whether coverage applies. Most policyholders never learn this distinction until a claim gets denied.

This guide covers how each policy form works, what retroactive dates and reporting requirements mean in practice, when tail coverage is necessary, which coverage types use which form, and how to evaluate the two structures when you have a choice.

What Is the Difference Between Claims-Made and Occurrence Insurance?

An occurrence policy covers incidents that happen during the policy period regardless of when the claim is filed. A claims-made policy covers claims that are made against you during the active policy period regardless of when the underlying incident occurred.

The timing question is what separates the two forms. With an occurrence policy, the date that matters is when the incident took place. With a claims-made policy, the date that matters is when the claim is made against you. A claim filed three years after an occurrence policy expires can still be covered. A claim filed one day after a claims-made policy lapses almost certainly won’t be.

Most policyholders don’t think about this until they need to. A business owner who carries claims-made coverage, lets the policy lapse, and then receives a demand letter has a problem that no amount of retroactive premium payment can fix. The reporting window closed when the policy did. 

Here’s an overview of the biggest differences between claims-made and occurrence insurance:

Individual carriers and specific policy types can vary from those patterns, and some coverage lines are available on both forms depending on the insurer.

How an Occurrence Policy Works

An occurrence policy covers any valid claim arising from an incident that took place during the period, regardless of when the claim is actually filed. Once the policy period closes, the coverage it provided for incidents during that period stays in place permanently. No renewal, no tail coverage, no additional action required. 

The incident date is the only date that matters under an occurrence form. A claim filed five years after the policy expired gets evaluated against one question only: did the incident happen while the policy was active? If the answer is yes, the policy responds. If the answer is no, it doesn’t. When the claim arrives is irrelevant.

Occurrence policies cost more upfront than claims-made policies for exactly that reason. The insurer is accepting open-ended exposure for incidents that happened during the policy period, whenever those incidents eventually surface as claims. That long-tail liability gets priced into the premium from day one.

Commercial general liability, commercial auto, and workers’ compensation are the coverage types most commonly written on an occurrence basis. For contractors specifically, GL on an occurrence form is the industry standard, which has direct implications for how completed operations claims get handled years after a project closes out.

Scenario: Roofing Subcontractor, Latent Defect

A roofing subcontractor completed work on a commercial building in 2022 under an occurrence-based GL policy. The policy expires in 2023 and the sub doesn’t renew. In 2025, the building owner discovers water infiltration behind the facade and traces the damage to the 2022 roofing work. The owner files suit.

The sub’s 2022 occurrence policy responds to the claim. The work happened during the policy period. The sub has no active coverage in 2025 and doesn’t need any. The occurrence form already locked in coverage for that project the moment the work was completed.

How a Claims-Made Policy Works

A claims-made policy covers claims that are made against you while the policy is active. The incident doesn’t need to happen during the current policy year, but the claim does need to be filed before the policy expires. Both conditions have to be satisfied for coverage to apply.

The policy must be active when the claim arrives. That single requirement is what creates the tail exposure that makes claims-made policies more complicated to manage than occurrence forms. A policyholder who carries claims-made coverage continuously for years, then lets it lapse, loses protection for every past incident that hasn’t yet generated a formal claim.

Claims-made policies start cheaper than occurrence policies because the insurer’s initial exposure is limited to claims filed in that first year. As the policy renews and the covered period extends further into the past, premiums rise through a process called step rating. By the sixth or seventh year, claims-made premiums typically reach parity with occurrence rates. The lower early-year cost is real, but it doesn’t last.

Claims-made policies are most commonly written for the following coverage types:

• Professional liability and errors and omissions
• Directors and officers liability (D&O)
• Employment practices liability (EPLI)
• Cyber liability

These lines carry long-tail exposure, where claims can surface years after the underlying act, which makes the claims-made form more manageable for insurers to price and reserve against. A design error in a building might not generate a claim for three years. An employment discrimination allegation can follow an executive for a decade. 

Insurers can’t price open-ended exposure on those risks the way they can on a GL policy where a slip-and-fall claim typically arrives within weeks. The claims-made form closes the reporting window at expiration, which gives insurers a defined liability horizon they can reserve against.

The cost trajectory in professional liability reflects how seriously insurers take that long-tail exposure. Nearly half of all medical liability premiums increased year-over-year in 2024, the highest proportion since 2005. The trend has been accelerating for six consecutive years, with 46 states seeing at least one premium increase in 2024 alone.

Scenario: Architect, Lapsed Policy

An architect carries professional liability insurance on a claims-made basis from 2020 through 2023, then lets the policy lapse. In 2024, a client files suit over a design error the architect made in 2022. 

The incident occurred during the policy. Under an occurrence form, that fact alone would trigger coverage. Under the claims-made form, it doesn’t. The policy wasn’t active when the claim arrived. Without tail coverage purchased at cancellation, the architect has no coverage for a claim arising from work they completed while fully insured.

What Is a Retroactive Date on a Claims-Made Policy?

A retroactive date is the earliest point from which a claims-made policy will cover incidents. Any claim arising from an act that happened before the retroactive date falls outside the policy’s coverage, regardless of when the claim is filed or whether the policy is active at the time.

The retroactive date stays fixed as long as you renew the same claims-made policy continuously. A professional liability policy that started in 2018 and has renewed every year since still carries a 2018 retroactive date. Every year of continuous renewal extends the window of covered past acts without pushing the retroactive date forward.

Resetting the retroactive date is one of the more consequential mistakes a policyholder can make at renewal. If an insurer moves your retroactive date from 2018 to 2024, every incident from 2018 through 2023 loses coverage. The new policy is active, but six years of past acts are now uninsured.

Some insurers offer full prior acts coverage, which eliminates the retroactive date entirely. All past acts are covered as long as the policy remains active, regardless of how far back they occurred.

When switching to a new insurer, carrying your retroactive date to the new policy requires the new carrier to endorse the policy with your original date. That endorsement is called prior acts coverage, and it preserves the coverage history you built under the previous policy. 

Here’s an example of what this looks like in practice:

1. You start a claims-made policy in 2018. Your retroactive date is January 1, 2018.
2. You renew continuously through 2024. Your retroactive date is still January 1, 2018.
3. In 2024, you switch insurers and purchase prior acts coverage. Your new policy carries the same January 1, 2018 retroactive date.
4. A claim filed in 2024 for an incident from 2020 is covered. The incident falls after the retroactive date and the policy is active when the claim is filed.

What Is a Nose?

A nose is prior acts coverage purchased from a new insurer that extends back to the retroactive date of a previous policy. When you switch insurers on a claims-made policy, a nose closes the gap between your old retroactive date and your new policy’s start date without requiring you to buy a tail from your previous carrier.

Both a nose and a tail address the same problem from opposite directions. A tail extends the reporting window on the old policy forward in time. A nose extends the coverage on the new policy backward in time. Which option makes more sense depends on the relative cost each insurer quotes and whether your new carrier is willing to honor your original retroactive date.

Reporting Requirements on a Claims-Made Policy

Claims-made policies impose strict reporting requirements, and missing a deadline by even a few days can result in a complete coverage denial. The policy doesn’t care why the claim was late. It cares whether it arrived within the reporting window.

Claims must be reported to the insurer during the active policy period or within any extended reporting period the policy provides. A claim reported one day after that window closes gets treated the same as a claim with no coverage at all.

The Near-Miss Scenario

A contractor notices a potential problem on a completed project in late November. They spend December investigating the scope before involving their insurer. The claims-made policy expires January 1. The formal demand arrives January 15.

Denied. The incident happened during the policy period. The investigation happened during the policy period. The formal demand didn’t arrive until after the policy expired, and that’s the only date a claims-made form cares about.

The Cost of a Missed Deadline

The stakes go beyond individual claim denials. In a 2023 First Circuit ruling involving Harvard University, the court confirmed that late notice to excess D&O carriers operated as a complete coverage bar at every layer, not just a basis for reducing what excess carriers owed. 

Harvard’s primary carriers paid its limits in full. The excess carriers paid nothing because the notification came too late. Courts enforce reporting deadlines on claims-made policies with very little sympathy for circumstances.

Most claims-made policies offer a practical safeguard worth knowing about. If you become aware of an incident that might generate a claim, you can report it to your insurer as a potential claim before it formally materializes. Filing that notification during the active policy period preserves coverage even if the formal demand arrives after the policy expires.

File early. File everything. The downside of an unnecessary notification is a brief conversation with your broker. The downside of a missed deadline is an uninsured claim.

Claims-Made and Reported Policies

A claims-made and reported policy is a stricter variant of the standard claims-made form. Under a standard claims-made policy, a claim needs to be filed against you during the policy period. Under a claims-made and reported policy, you also need to report that claim to your insurer before the policy expires. Both events have to occur within the same policy period for coverage to apply.

Most policyholders assume they’re on a standard claims-made form and don’t discover otherwise until a reporting deadline passes. The distinction isn’t prominently labeled. It lives in the policy language, and the difference between “claims-made” and “claims-made and reported” in a policy document can look like boilerplate to anyone who isn’t reading carefully.

If you carry professional liability, D&O, or cyber coverage, check your policy language before assuming the standard claims-made rules apply. The reporting obligations your policy imposes are only as forgiving as the form it’s written on.

What Is Tail Coverage and When Do You Need It?

Tail coverage is how policyholders protect themselves against claims that surface after a claims-made policy ends, and knowing how claims-made vs. occurrence tail coverage differs is what separates a covered claim from a denied one when a policy lapses. When a claims-made policy is canceled or not renewed, the reporting window closes with it. Any incident that occurred during the policy period but hasn’t yet generated a formal claim becomes uninsured the moment the window shuts. Tail coverage reopens it.

Formally called an extended reporting period (ERP), tail coverage is an endorsement purchased at policy cancellation that extends the window during which claims can be reported. The underlying coverage doesn’t change. The incidents that qualify for coverage are still limited to those that occurred during the original policy period. What changes is how long you have to report them.

Tail coverage becomes necessary in four situations:

• You retire and cancel your policy
• You change careers
• Your business closes permanently
• You switch insurers without purchasing prior acts coverage from the new carrier

In any of those scenarios, a claims-made policy without a tail leaves past incidents uninsured the moment coverage lapses.

The cost is huge. The AMA Insurance Agency advises physicians that purchasing tail coverage separately typically costs 150% to 200% of the final-year claims-made premium as a one-time lump sum. Physicians negotiating employment contracts are advised to require their employer to contractually commit to covering the tail premium at departure. 

The scenario that plays out when they don’t is common enough to have become a recurring warning in medical liability circles. A physician spends several years at a practice, transitions to a new opportunity, and only then discovers they owe a lump sum tail premium equal to twice their final year’s coverage cost. 

The bill arrives at exactly the moment they’re absorbing the financial disruption of a career transition and have the least capacity to absorb an unplanned expense. Arranging tail coverage responsibility in the employment contract before signing is the only reliable way to avoid it.

Extended and Free Tail Options

Some insurers offer a supplemental extended reporting period (SERP) endorsement that extends the reporting window beyond the standard tail period, sometimes indefinitely. And some carriers provide tail coverage at no cost under specific circumstances, including retirement, death, or permanent disability, provided the policyholder meets the carrier’s eligibility requirements and notifies them within the required timeframe.

Occurrence policyholders don’t need tail coverage. The occurrence form already guarantees coverage for incidents that happened during the policy period regardless of when the claim arrives. There’s no reporting window to extend.

How tail coverage requirements differ between occurrence and claims-made policies depends on the situation you’re in when coverage ends:

Claims-Made vs. Occurrence: Two Scenarios That Show the Difference

The distinction between claims-made and occurrence policies is easiest to understand through specific claim situations where the outcome depends entirely on which form applies. The facts of the incident don’t change. The coverage does.

The Construction Defect Claim

A general contractor hires a waterproofing subcontractor for a commercial project that completes in 2021. The sub carries a GL policy on an occurrence basis during the project. The policy expires in 2022, and the sub moves on to other work without renewing.

In 2024, the building owner discovers pervasive water infiltration behind the facade and traces the damage to the waterproofing work. The owner files suit against both the GC and the sub. 

The sub’s 2021 occurrence policy responds. The work happened during the policy period, and that’s the only date an occurrence form cares about. The sub has no active coverage in 2024 and doesn’t need any.

Now run the same scenario with a claims-made GL policy (rare, but they exist) and no tail coverage. The claim arrives in 2024. The policy lapsed in 2022. The reporting window closed with it. The sub is uninsured for a claim arising from work they completed while fully covered, and the GC faces the prospect of absorbing a loss that should have been the sub’s insurer’s problem entirely.

Faulty workmanship and maintenance rank among the most expensive causes of liability claims across the insurance industry, sitting alongside defective product incidents as a top driver of large losses. Nuclear verdicts exceeding $10 million grew by more than 27% in 2023. The financial stakes behind a lapsed sub’s policy aren’t hypothetical. 

This is why construction contracts require completed operations coverage specifically, and why the endorsement form number on a subcontractor’s certificate of insurance (COI) matters more than most GCs realize until a claim comes up.

The Medical Malpractice Claim

A physician carries professional liability insurance on a claims-made basis from 2018 through 2022, then retires and cancels the policy without purchasing tail coverage. In 2023, a former patient files a malpractice claim for treatment provided in 2021.

The treatment occurred during the policy period. Under an occurrence policy, that fact alone would trigger coverage. Under the claims-made form the physician carried, it doesn’t. The policy wasn’t active when the claim arrived, and without a tail, there’s no coverage for work performed while fully insured.

The exposure this creates is substantial. Almost one-third of all U.S. physicians had been sued at least once as of 2022. Among physicians over 54, nearly half had faced a lawsuit. A retiring physician canceling a claims-made policy without tail coverage is walking away from protection against a category of claim that affects roughly one in three colleagues over the course of a career.

The physician in this scenario faces personal liability for a claim that a tail premium would have fully covered. Most malpractice insurers emphasize this at cancellation precisely because the scenario is common enough that they’ve seen the consequences play out too many times to stay quiet about it.

Which Policy Types Use Claims-Made vs. Occurrence Forms?

For most policyholders, the policy form isn’t a choice. The type of coverage determines the form, and understanding which form applies to each policy in your program is part of managing your risk properly.

The coverage types in your program and the forms they typically use are as follows:

Every claims-made line in that table shares a common characteristic. The harm they cover tends to come up long after the underlying act happened, and insurers can’t price or reserve for claims that might arrive years after the policy expires. Closing the reporting window at expiration is what makes these coverage lines commercially viable to write at all.

The D&O data makes this concrete. Securities class action filings increased 15% in 2024, reaching 225 filings, with settlements in the first half of 2024 alone totaling $2.1 billion. Thirteen of the eighteen largest shareholder derivative settlements in US history landed in the past five years. A D&O claim filed today over a board decision from three years ago is entirely routine. An insurer writing that exposure on an occurrence basis would be holding reserves against claims with no defined arrival window.

EPLI follows the same pattern. The EEOC received 88,531 new discrimination charges in fiscal year 2024, a 9.2% increase over the prior year, recovering nearly $700 million for more than 21,000 workers. Employment discrimination allegations routinely surface months or years after the conduct in question. The claims-made form exists precisely because that gap between act and claim is unpredictable and potentially very long.

Construction firms face the same dynamic on professional indemnity. An Allianz analysis of more than 93,000 professional indemnity claims across two decades identified construction as one of the industries most impacted by large PI losses globally, with architects and engineers facing growing scrutiny over building and fire safety defects. A structural design error might generate a claim five years after project completion. Occurrence-based professional indemnity would require insurers to hold reserves indefinitely for every project an architect has ever touched.

Cyber liability adds another layer of complexity. A breach generates immediate costs, but the downstream professional indemnity claims from clients alleging business interruption losses or exposed confidential data arrive well after the breach itself. Allianz identifies this as a compound exposure where the triggering event and the resulting liability claims operate on completely different timelines. Writing cyber liability on an occurrence basis would leave insurers exposed to cascading claims with no defined endpoint. The claims-made form is the only structure that contains the exposure to a manageable window.

How to Find Out Which Policy Form You Have

Most policyholders don’t know which form their policy is written on until they go looking for it. The good news is that the answer is on the first page of your policy.

Pull out your declarations page, which is the summary document at the front of your policy that lists your coverage details, limits, and policy period. Look for the words “occurrence” or “claims-made” in the policy form section. Most declarations pages make this explicit. If yours doesn’t, look for a retroactive date. A retroactive date on a liability policy is a reliable indicator that you’re on a claims-made form. Occurrence policies don’t have them.

If you can’t locate your declarations page, call your broker and ask directly. The question takes thirty seconds to answer. The implications of not knowing can be significantly more costly.

Professional liability, D&O, EPLI, and cyber policies are almost always claims-made. If you carry any of those lines and have never thought about tail coverage, that’s worth revisiting before your next renewal. A policy that’s been quietly renewing on a claims-made basis for years creates tail exposure that grows larger every year it goes unaddressed.

How to Evaluate Claims-Made vs. Occurrence When You Have a Choice

Where a genuine choice exists between claims-made and occurrence coverage, the decision comes down to four practical factors. Most policyholders don’t get to choose, but when the option exists, working through these considerations will point you toward the right answer for your situation:

1. Total cost of ownership: Claims-made policies start cheaper, but the annual premium comparison misses the full picture. Tail coverage typically costs 150% to 200% of the final year’s premium as a one-time lump sum. A policyholder who carries a claims-made policy for ten years and then cancels without a free tail option will pay a significant exit cost that narrows or eliminates the premium savings accumulated over the policy’s life.
2. Business stability: Contractors and professionals who switch insurers frequently face repeated tail exposure on claims-made policies. Every carrier transition without a nose from the new insurer creates a gap that requires a tail from the old one. Occurrence coverage sidesteps this entirely. The policy you had during the work period covers the work period, regardless of what you do next.
3. Coverage continuity: A claims-made policy that lapses briefly creates a gap that’s expensive to close retroactively. Prior acts coverage from a new carrier can restore some of that history, but the terms depend entirely on what the new carrier is willing to offer. Occurrence policies carry no equivalent risk. A lapsed occurrence policy still covers incidents that happened while it was active.
4. Limit flexibility: Claims-made policies allow you to increase your limits at renewal and have the higher limits apply to past acts going forward. With an occurrence policy, the limits in place at the time of the incident are the limits that apply to any claim arising from it, regardless of what you carry later.

Professional liability carriers entering 2024 were reporting adverse severity trends across most lines, with social inflation cited as the primary driver. Underwriters flagged specific concern about nuclear verdicts in professional and product liability, with mid-single-digit rate increases predicted across PL lines. For anyone evaluating claims-made coverage in that environment, the total cost of ownership calculation deserves serious attention before the first premium payment is made.

Claims-Made and Occurrence Policies on Certificates of Insurance

When you receive a COI from a subcontractor or vendor, the policy form listed on that certificate directly affects how you evaluate their compliance. An expiration date means something different depending on whether the underlying policy is written on an occurrence or claims-made basis, and treating the two the same way is a compliance error that most manual review processes never catch.

A subcontractor’s occurrence-based GL policy that expired after project completion may still cover latent defects that come up years later. The work happened during the policy period, and that’s what the occurrence form protects. A sub whose claims-made professional liability policy lapsed after project closeout has no coverage for design-related claims that arrive after the reporting window closed, regardless of when the underlying error occurred.

For GCs managing completed operations exposure across larger subcontractor rosters, this distinction matters on every project that involves design-build subs, engineers, or specialty contractors carrying professional liability on a claims-made basis. The project might be closed. The sub’s policy might have expired. The claim can still arrive, and whether coverage exists depends entirely on what form that policy was written on and whether a tail was purchased.

Tracking policy form alongside expiration dates is part of complete COI compliance, and it’s a step that spreadsheet-based processes almost never take. Most COI reviews confirm that a policy exists and that it hasn’t expired. They don’t record whether the policy is occurrence or claims-made, and they don’t flag when a claims-made policy lapses without evidence of tail coverage on a recently completed project.

CertFocus by Vertikal RMS tracks policy types, expiration dates, and compliance status across both occurrence and claims-made policies across your entire subcontractor roster. When a claims-made policy lapses on a sub with active or recently completed project exposure, CertFocus by Vertikal will identify the issue, and the system will trigger automated follow-ups.

Putting It All Together

The difference between claims-made and occurrence coverage isn’t a technical footnote buried in your policy documents. It determines whether a claim that arrives after your policy ends gets covered or denied, and the consequences of getting it wrong fall entirely on the policyholder.

For most businesses, the policy form is determined by the type of coverage and the choice doesn’t exist. What does exist is the responsibility to know which form each policy in your program is written on, what that means for your tail exposure, and what happens if a policy lapses without the right coverage in place.

For contractors and GCs managing subcontractor compliance, the stakes go way beyond your own program. A sub’s expired occurrence GL policy may still cover completed work. A lapsed claims-made professional liability policy almost certainly won’t. Tracking which form each sub carries, and what happens when those policies expire, is part of managing completed operations exposure properly.

CertFocus by Vertikal RMS monitors policy forms alongside expiration dates across your entire subcontractor roster, flagging when claims-made policies lapse on subs with recent project exposure. If your team is managing COI compliance at scale, it’s worth seeing how the platform handles it.

Frequently Asked Questions About Claims-Made and Occurrence Policies