Stop-Loss Insurance for Employers: What It Is and When You Need It

Key Takeaways

• Stop-loss insurance reimburses a self-funded employer once medical claims pass an agreed threshold, putting a ceiling on what one catastrophic case or one bad year can cost the plan.
• Specific stop-loss coverage caps what the employer pays for any one person, while aggregate stop-loss coverage caps what the employer pays for the whole plan over the contract year.
• A stop-loss policy decides who pays for a catastrophic claim after it happens, but it does nothing to make that claim less likely or less severe.

A self-funded employer pays its own medical claims instead of a fixed premium. That works fine until one employee's treatment costs over $3 million. Stop-loss insurance is what keeps a self-funded plan solvent when that happens. It caps how much of a catastrophic claim, or a catastrophic year, the plan has to absorb, making it a core design decision for any self-funded employer.

Getting that decision right means understanding what stop-loss covers, how specific and aggregate coverage differ, and what happens at renewal after a bad year. That last part matters most. Stop-loss insurance protects the budget from a bad claims year, but it does nothing to make a bad year less likely. And the carrier prices next year's contract on the current year’s claims, so a bad year will still raise the price of your premium eventually.

What is stop-loss insurance?

A fully insured employer pays a premium, and the carrier owns the claims. On the other hand, a self-funded employer keeps the premium and pays the claims itself. That saves money in an average year and leaves no ceiling in a bad year. KFF's 2025 Employer Health Benefits Survey puts 67% of covered workers in self-funded plans, rising to 80% at large firms. Every one of those plans needs a ceiling on what a bad year can cost, and stop-loss insurance is that ceiling. 

The employer buys a policy from a stop-loss carrier that reimburses the plan once claims cross a defined threshold. Below that threshold, the plan keeps paying. Above it, the carrier takes over. Level-funded plans use the same structure with a much lower threshold, giving smaller employers a predictable monthly payment.

In the current medical climate, claims big enough to cross that threshold are arriving more often than ever. Sun Life's 2026 high-cost claims report, drawn from more than 70,000 high-dollar claims across 3,300 self-funded employers, found that million-dollar claims grew 46% in frequency between 2022 and 2026. And Segal's 2026 stop-loss dataset of 225 plans shows the number of seven-figure claimants growing 25% a year over the last four years. So an employer with 400 employees and no stop-loss policy is one premature birth or one cancer diagnosis away from a claims bill it never budgeted for.

Specific vs. aggregate stop-loss coverage

Specific stop-loss covers one person and aggregate stop-loss covers the whole plan. Everything else in the two contracts follows from that difference.

Most employers buy specific coverage alone. Mployer's 2026 analysis of more than 50,000 employers found that 92% of self-funded employers carry specific-only stop-loss, while just 8% carry both. That split comes down to group size. A large group has enough covered lives that its total claims land close to expected in most years, so aggregate coverage rarely pays out. A 150-person group's claims swing much more from year to year, and a handful of mid-sized claims that never touch the specific deductible can still push it well past budget. So for a group that size, a cap on the whole year's claims is worth the premium.

How attachment points and deductibles are set

The specific deductible is the most important number in the contract, and the carrier doesn't set it alone. Underwriters look at group size, the plan's claims history, any known high-cost claimants, and how much of a bad year the employer's reserves can cover. The employer then decides how much of that risk to keep. A lower deductible means the carrier takes over sooner, and the premium goes up, while a higher deductible means the plan keeps more of each large claim and pays the carrier less.

In the 2026 Aegis Risk survey of 1,378 stop-loss policies, the average premium for a $100,000 specific deductible was $260.63 per employee per month, compared with $58.82 for a $500,000 deductible. Mployer puts the average specific deductible at $141,938 for self-insured plans and $46,318 for level-funded plans. Those averages are a starting point for your own renewal. A deductible well below them means you're paying the carrier to hold risk you could probably carry yourself. One well above them means a single bad claimant lands mostly on your budget.

What stop-loss does, and what it doesn't

A stop-loss contract settles who pays for a catastrophic claim, and nothing more. Above the deductible, the carrier pays. Below it, the plan pays. Stop-loss moves financial risk, and every self-funded plan needs it to, but moving a cost to a carrier isn't the same as lowering the cost.

That difference shows up in the premium. An employer can hold excellent coverage and collect every reimbursement it's owed, and its stop-loss premium will still climb year after year. That's because the carrier prices next year's contract on what the plan's claims looked like last year. Segal's 2026 data puts the average stop-loss premium increase at 12.7% for groups that kept a similar deductible, up from 9.7% the year before. So as long as high-cost claims keep growing across your population, the coverage that protects you from them keeps getting more expensive.

How stop-loss carriers reprice after a bad claims year

A year with one or two large claimants shows up in the very next renewal quote. The carrier now knows about an ongoing cancer treatment or a specialty drug that CBIZ estimates at $500,000 to $1 million or more per patient per year. It expects at least some of that cost to continue, so it asks for a higher premium, a higher deductible, or both.

A second effect, which underwriters call leveraged trend, pushes premiums up even for groups with a clean year. Medical inflation makes every claim bigger, but the deductible stays fixed, so the carrier's share of a large claim grows faster than the claim itself. Take a claim that rises 10%, from $200,000 to $220,000. With a $150,000 deductible, the carrier's share goes from $50,000 to $70,000, a 40% increase on a 10% rise in cost. Carriers build that into every renewal, and it's one reason stop-loss premiums rise faster than medical costs.

What lasering means for a high-cost claimant

Nothing shows the limits of stop-loss more clearly than lasering. When a carrier spots a covered person who is likely to generate large claims next year, it can assign that person a higher specific deductible than the rest of the group. In some cases, it excludes the person from coverage entirely. The employer's plan then carries most or all of that person's cost. The treatment doesn't change, and the claim doesn't shrink. It simply moves back onto the employer's books.

Some contracts include a no-new-lasers provision that stops the carrier from adding lasers at renewal, usually bundled with a rate cap and a higher premium. That helps with budgeting, but it's still a negotiation about who pays. Nothing in the contract touches what happens to the patient, and that's where the cost of the claim is actually decided.

Reducing the underlying risk, not just the financial exposure

The cost of a catastrophic claim is set in the exam room and the operating room long before it reaches the stop-loss carrier. The surgeon who operates, the evidence the oncologist follows, and the complications that send a patient back to the hospital all end up in the final bill. Garner's analysis of how differently doctors perform found that the top 25% of physicians within the same hospital system order 70% less low-value care than their lowest-performing peers. Low-value care means the tests and procedures the evidence says a patient didn't need. And Sun Life lists cancer, musculoskeletal conditions, and premature birth among the most common sources of claims above $3 million, all conditions where the choice of doctor changes the bill.

None of this replaces stop-loss. However, a better claims history earns better renewal terms, and which doctor treats a high-cost case is one of the few things an employer can influence before the claim gets large. Garner's report on what is driving healthcare costs for employers estimates that low-quality care alone adds 1.7% to employer spend each year, and no stop-loss contract can touch that share.

How Garner fits alongside existing stop-loss coverage

Garner identifies the best-performing doctors already in an employer's network and helps cover employees' out-of-pocket costs when they see those doctors. It sits on top of the existing plan with no network changes required, so the carrier, plan design, and stop-loss contract all stay exactly as they are. The incentive guides employees to Top Providers in the specialties most associated with catastrophic claims, and those are the cases where the doctor matters most to the final cost.

An Aon study comparing Garner-eligible employees against a matched control group between 2020 and 2024 found 7.4% lower medical spend, or $345 less per member per year, in the first year. Members with two or more chronic conditions, the group most likely to become next year's high-cost claimants, spent $648 less per member per year. And lower, steadier claims are exactly what a stop-loss underwriter wants to see at renewal.

Building a stop-loss strategy that accounts for what drives claims

A strong stop-loss program protects this year's budget, while a strong provider quality program protects the claims history that sets the price of that protection next year. Renewal negotiations tend to center on the attachment point, the laser list, and the rate cap, and those terms decide who pays for a bad year. However, the harder question is what's driving your high-cost claims, and whether anything can be done about it before the next one arrives. If you're still moving from fully insured to self-funded, that question belongs in the plan design conversation from the start.

Want a clearer picture of what's driving your high-cost claims before your next stop-loss renewal? Book a demo to see how Garner works alongside your existing plan and stop-loss coverage.

FAQs

Who needs stop-loss insurance?

Virtually any employer that pays its own medical claims rather than a fixed premium needs stop-loss insurance. Without it, a single multimillion-dollar claim lands entirely on the plan. Most self-funded employers, whatever their size, carry at least specific coverage.

What's the difference between specific and aggregate stop-loss?

Specific stop-loss caps what the plan pays for any one covered person during the contract year, reimbursing claims above a per-person deductible. Aggregate stop-loss caps what the plan pays in total across all claims, reimbursing once combined claims pass an attachment point usually set at 115% to 125% of expected claims. So specific coverage protects against a single catastrophic case, while aggregate protects against many mid-sized claims arriving in the same year.

How is a stop-loss deductible or attachment point determined?

Carriers set the specific deductible based on group size, the plan's claims history, known high-cost claimants, and how much risk the employer wants to keep. The average specific deductible for self-insured plans was $141,938 in Mployer's 2026 data. Raising the deductible lowers the premium but leaves the plan paying more of each large claim.

What happens if an employer doesn't have stop-loss insurance?

The plan pays every dollar of every claim with no ceiling. A single premature birth or cancer case can now exceed $3 million, and that cost comes out of the employer's operating budget or reserves in the year it occurs. For most self-funded groups, a single bad year could erase several years of self-funding savings.

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