Answer-first summary: An occurrence policy covers claims arising from incidents that happen during the policy period, no matter when the claim is later filed. A claims-made policy covers claims only if both the incident occurred on or after the retroactive date AND the claim is reported while the policy is active. Who this is for: business owners, contractors, and professionals shopping for general liability, professional liability, or medical malpractice coverage.
TL;DR — Key Takeaways
- Occurrence = the incident date controls coverage; reporting can happen years later with no gaps.
- Claims-made = the reporting date controls coverage; if the policy lapses, you may need tail coverage (an Extended Reporting Period, or ERP).
- General liability (GL) and commercial auto are most often written on an occurrence basis; professional liability (E&O), D&O, EPLI, and cyber are almost always claims-made.
- Claims-made premiums start lower in year 1 and typically reach parity with occurrence pricing by policy year 5–6.
- Switching carriers mid-stream on a claims-made policy requires careful handling of "nose" or "tail" coverage to avoid gaps.
What Is an Occurrence Policy?
An occurrence policy pays for covered bodily injury or property damage that physically occurs during the policy period, regardless of when the victim files a claim or the lawsuit arrives. If a pipe you installed bursts in 2024 and the resulting water-damage claim isn't filed until 2027, your 2024 occurrence policy responds — even if you've since moved to a different insurer.
This simplicity is one of its biggest advantages: once the policy year closes, that coverage year is "locked in" forever. No need to buy additional reporting tail.
Occurrence is standard on: - Commercial General Liability (CGL) - Commercial auto - Workers compensation - Commercial property (though property is technically a "direct damage" trigger, not occurrence vs. claims-made)
What Is a Claims-Made Policy?
A claims-made policy pays for claims that are both (a) triggered by an act or incident on or after the retroactive date and (b) formally reported to the insurer while the policy is in force (or within any purchased extended reporting window).
Two dates matter on every claims-made certificate:
| Date | What It Controls |
|---|---|
| Retroactive date | How far back prior acts are covered; often set to the first day you originally bound claims-made coverage with any carrier |
| Policy expiration date | Last day a new claim can be reported under the base policy |
Claims-made is standard on: - Professional Liability / E&O - Directors & Officers (D&O) - Employment Practices Liability (EPLI) - Cyber liability - Medical malpractice - Some umbrella/excess layers
How Claims-Made Step Factors Work (Pricing Over Time)
Claims-made premiums are not flat. Insurers apply a "step factor" — each year the policy matures, the premium rises to reflect the growing tail of potential prior-act claims, until reaching what carriers call the mature rate (roughly year 5 or 6).
| Policy Year | Typical Step Factor vs. Mature Rate | Illustrative Annual Premium (E&O, $1M/$2M, small consulting firm) |
|---|---|---|
| 1st year | ~25–35% of mature rate | $800 – $1,200 |
| 2nd year | ~50–60% of mature rate | $1,600 – $2,400 |
| 3rd year | ~70–75% of mature rate | $2,200 – $3,000 |
| 4th year | ~85–90% of mature rate | $2,700 – $3,600 |
| 5th year+ | ~100% (mature) | $3,200 – $4,500 |
Premiums are illustrative ranges; actual quotes vary by revenue, risk class, claims history, and carrier. Ask Morrow for a bindable quote.
The low first-year cost can make claims-made attractive to startups, but buyers must budget for rising premiums and account for the tail cost when switching or closing the business.
Tail Coverage (Extended Reporting Period) Explained
When a claims-made policy ends — because you switched carriers, retired, or sold the business — incidents from your prior policy period can still generate claims for years. Without protection, those future claims fall into a coverage gap.
Tail coverage (also called an Extended Reporting Period, ERP) is an endorsement or standalone policy that extends the window to report claims after the base policy expires. The trigger date (retroactive date) stays the same; only the reporting window stretches.
How to purchase tail coverage in 5 steps:
- Confirm your retroactive date on the expiring policy certificate — this anchors what acts are covered.
- Request a tail quote from your current carrier at least 30 days before expiration; most carriers offer 1-, 3-, and 5-year tails, with unlimited options available for some professions.
- Compare the tail cost against a "nose" endorsement (prior acts coverage) from your new carrier, which can achieve the same protection by extending your new policy's retroactive date backward.
- Bind before the policy lapses — most carriers allow a brief grace period (commonly 30–60 days) to purchase tail, but check your specific policy language.
- Retain proof of tail in your records permanently, since professional liability claims can surface 5–10 years after the act.
Typical tail cost: 100–250% of the final annual premium, paid as a one-time lump sum, depending on profession, reporting tail length, and carrier. Medical malpractice tails tend to run at the higher end of that range.
Side-by-Side Comparison
| Feature | Occurrence Policy | Claims-Made Policy |
|---|---|---|
| Coverage trigger | Incident occurs in policy period | Claim reported while policy is active |
| Prior acts coverage | Automatic (if incident was in policy period) | Requires retroactive date going back far enough |
| Post-policy reporting | No action needed | Tail coverage or ERP required |
| Year-1 premium vs. occurrence | Higher (full mature rate) | Lower (step factors apply) |
| Coverage gap risk | Very low | Moderate — gaps possible on carrier switches |
| Common lines | GL, auto, WC | E&O, D&O, EPLI, cyber, med mal |
| Complexity to manage | Low | Moderate — track retro date, expiration, tail |
Real-World Scenario: IT Consultant in Texas
This is an illustrative example, not a guarantee of coverage or pricing.
Maria runs a 10-person IT consulting firm in Austin, TX. She buys a claims-made professional liability (E&O) policy effective January 1, 2021, with a retroactive date of January 1, 2021.
- 2021–2025: She renews annually with the same carrier; premiums step up each year.
- January 2026: She lands a large contract and switches to a carrier offering broader tech E&O terms. Her new policy has a retroactive date of January 1, 2021 (matching her original date) — this is "nose" coverage protecting her prior acts without buying tail from the old carrier.
- March 2026: A client alleges a data breach caused by a 2023 implementation error and files a claim. Her 2026 policy responds because the retroactive date covers the 2023 act and the claim is reported in 2026 while the policy is active.
- Outcome: The carrier defends the suit, eventually settling for $185,000 within the $1M per-claim limit. No coverage gap because the retroactive date was preserved on the carrier switch.
Had Maria failed to confirm the retroactive date when switching carriers — a common mistake — the 2023 incident would have been uninsured.
FAQ
Q: Can I have an occurrence general liability policy AND a claims-made professional liability policy at the same time? Yes, and this is extremely common. A design-build contractor, for example, typically carries occurrence-based CGL for job-site bodily injury and property damage, plus claims-made professional liability for design errors and omissions. The two policies use different trigger forms and respond to different types of claims.
Q: What happens if I close my business and never buy tail coverage? Any claim reported after your claims-made policy expires — even for work you did years ago — will be denied for lack of coverage. For professions with long "discovery" periods (architects, engineers, attorneys, physicians), this can be financially catastrophic. Most carriers offer run-off tail; unlimited tails are available for some classes.
Q: Is occurrence coverage always better than claims-made? Not necessarily. For professional liability lines, the market largely writes only claims-made forms — occurrence-based E&O barely exists. Where you do have a choice (some umbrella and excess markets), occurrence locks in coverage permanently but often costs more in year 1. Claims-made can be cost-effective for new businesses if you budget for the tail.
Q: What is a "prior acts" or "full prior acts" endorsement? It is a claims-made endorsement that sets the retroactive date to the very beginning of your business — or even unlimited prior acts — so all past professional services are covered, not just those since the retroactive date. It typically adds a modest premium surcharge and is especially important when you are a new business buying E&O for the first time.
Q: Does my general liability occurrence policy cover professional errors? Standard CGL occurrence forms explicitly exclude professional liability (they cover bodily injury and property damage, not economic losses from professional advice or services). You need a separate professional liability / E&O policy, almost always written claims-made, to cover professional errors.
Q: What is a "reporting date" vs. an "occurrence date" for claim purposes? On an occurrence policy, the insurer asks: when did the bodily injury or property damage occur? On a claims-made policy, the insurer asks: when was the claim first made against you and reported to us? Both dates appear on the claim form — the controlling date depends on which trigger form your policy uses.
Q: How does tail coverage affect the sale of a professional practice? When selling a professional practice — medical, legal, accounting, engineering — the seller typically buys an unlimited tail so all prior-act claims are insured after the sale. The cost is often negotiated as part of the purchase agreement. Buyers should verify the seller's tail is in place before closing.
Q: Does workers compensation use occurrence or claims-made? Workers compensation policies in the United States are written on an occurrence basis (more precisely, an "injury date" trigger). There is no claims-made workers comp form in standard markets. This means you do not need tail coverage when switching WC carriers.
Why Morrow
- Independent agency, multiple carriers. Morrow places coverage across a broad panel of admitted and E&S carriers, meaning we can compare occurrence and claims-made options side by side — including carriers that offer occurrence-equivalent forms in specialty lines — rather than steering you toward a single insurer's product.
- Retroactive date tracking. We maintain your retroactive date history so that every renewal and carrier switch preserves your prior-acts coverage. No accidental gaps.
- Tail cost modeling at renewal. Before you ever decide to switch carriers, Morrow runs a tail vs. nose cost comparison so you can make an informed financial decision — not an expensive surprise after the fact.
- Real claims advocacy. When a claim crosses the trigger boundary — late-reported, retroactive date disputes, duty-to-defend questions — Morrow advocates directly with the carrier claims team on your behalf.
- Fast certificates. When a contract requires proof of your retroactive date and extended reporting period, Morrow issues compliant certificates of insurance (COIs) quickly. [Morrow to confirm typical turnaround SLA.]
Get a Quote
Ready to compare occurrence and claims-made options for your business? Get a quote from Morrow in minutes — we'll match you with the right trigger form and carrier for your profession and risk.
Trust strip: Morrow (Afthonea Inc., DBA Morrow) is a licensed independent commercial P&C insurance agency. [Morrow to confirm: licensed states, NPN, and carrier panel.] Carriers placed include admitted and specialty E&S markets. Reviews available on [Morrow to confirm review platform].
Related Pages
- Commercial General Liability Insurance — occurrence-based GL explained
- Professional Liability / E&O Insurance — the most common claims-made line
- Cyber Liability Insurance — claims-made form, unique trigger considerations
- Directors & Officers (D&O) Insurance — claims-made, side A/B/C structure
- Insurance Glossary: Extended Reporting Period (Tail Coverage)
Author: [Morrow Editorial Team — P&C licensed author name to be confirmed by Morrow] Published: June 2026 | Last updated: June 2026
Sources: - Insurance Services Office (ISO) CGL policy form CG 00 01 (occurrence trigger language) - Insurance Services Office (ISO) claims-made CGL coverage form CG 00 02 - National Association of Insurance Commissioners (NAIC) — claims-made policy guidance - Texas Department of Insurance (TDI) — consumer publications on professional liability - Insurance Information Institute (III) — "What is Claims-Made Coverage?" - American Bar Association — "Tail Coverage and the Ethics of Lawyer Malpractice Insurance" - Individual carrier rate and rule filings (filed with applicable state DOIs)