How Stop-Loss Coverage Works in Self-Funded Health Plans — The Safety Net Every Growing Company Should Understand

If your company has between 20 and 150 employees and you're spending $1,400 to $2,000 per employee each month on group health coverage, you've almost certainly heard that self-funded health plans can cut those costs by 10% to 20%. The math is compelling. But when most business owners hear "self-funded," the same fear surfaces: what happens if one of your employees is diagnosed with cancer, has premature twins, or needs a $400,000 organ transplant?

Stop-loss coverage is the answer to that question. It's the financial safety net that makes self-funding practical — even for employers with fewer than 100 employees — by capping how much your company pays in any single plan year, both for individual catastrophic claims and for total aggregate claims across your entire workforce. Most business owners exploring self-funded arrangements have heard the term, but very few understand how it actually works, who sets the premiums, and how the attachment points get calibrated to their specific group.

This guide walks through everything you need to know: the two types of stop-loss protection, how attachment points work, what drives premium costs, how PEOs integrate stop-loss coverage into their arrangements, and a decision framework for evaluating whether self-funding with stop-loss protection fits your company's financial profile and risk tolerance.

What Is a Self-Funded Health Plan?

In a traditional fully-funded group health plan, you pay a fixed monthly premium to a carrier — let's say $1,600 per employee. The carrier takes on all the risk. If your group has a great claims year, the carrier keeps the profit. If your group has a catastrophic year, the carrier absorbs the loss. Your cost is predictable, but you're paying for that certainty at a significant markup.

In a self-funded plan, you pay your employees' actual medical claims directly through a third-party administrator (TPA). You also pay a fixed monthly fee for plan administration, stop-loss coverage premiums, and network access fees. If your claims are lower than projected, you keep the difference. If they're higher, stop-loss coverage steps in after your deductible layer absorbs the first portion.

According to the Kaiser Family Foundation's 2023 Employer Health Benefits Survey, 65% of covered workers at firms with 200 or more employees are enrolled in self-funded plans. Among firms with 100–199 employees, self-funding covers about 37% of workers — and adoption is growing. AHIP data indicates self-funded employers typically pay 8% to 15% less per covered member compared to fully-funded arrangements, even after factoring in stop-loss costs.

The Two Types of Stop-Loss Protection

Specific Stop-Loss Coverage

Specific stop-loss (also called individual stop-loss) protects your company against a single employee's catastrophic claims in a given plan year. You choose a specific deductible — the per-person threshold your plan pays before the stop-loss carrier reimburses you for the remainder.

For example, if your specific deductible is $75,000 and an employee has $280,000 in surgical and rehabilitation claims, your plan pays $75,000 of that claim and the stop-loss carrier reimburses you for the remaining $205,000. You're protected against any one person's catastrophic situation draining the plan's financial reserves for the year.

Common specific deductible levels by group size:

• 30–50 employees: $25,000 to $50,000 per person (lower deductible = higher stop-loss premium)
• 50–100 employees: $50,000 to $100,000 per person
• 100–200 employees: $75,000 to $150,000 per person

The relationship between deductible level and premium is inverse: a lower specific deductible means the stop-loss carrier takes more risk and charges a higher monthly premium. A higher deductible means you retain more risk but pay less for coverage. Your TPA or benefits advisor can model the break-even point for your specific group demographics and claims history.

Aggregate Stop-Loss Coverage

Aggregate stop-loss protects against total claims across your entire workforce exceeding a defined threshold — typically set at 125% of projected annual claims. This is your company-wide safety net: even if no single person crosses the specific deductible, aggregate stop-loss kicks in if your overall plan has an unexpectedly bad year.

Here's how it works in practice. If your TPA projects $1.2 million in total annual claims for your 75-person workforce, your aggregate attachment point would be set at approximately $1.5 million (125% of projected claims). If total claims for the year come in at $1.8 million — perhaps because of a cluster of high-cost maternity cases, orthopedic surgeries, or specialty medication users — the aggregate stop-loss carrier reimburses you for the $300,000 above the attachment point.

Aggregate stop-loss is what separates a viable self-funded plan from an unlimited liability exposure. Without it, a statistically unlikely but possible scenario — like five employees with serious diagnoses in the same plan year — could generate claims multiples above your projections with no ceiling on your cost.

How Attachment Points Are Set — And Why It Matters

The specific deductible and aggregate attachment point aren't arbitrary numbers. Stop-loss carriers and TPAs set them using actuarial modeling based on:

• Group demographics: Age, gender, and geographic distribution of your workforce
• Industry risk factors: Claims patterns for your SIC code — construction groups have different expected claim distributions than office-based companies
• Prior claims history: 24–36 months of claims data is the gold standard; newer employers may need to accept higher attachment points
• Plan design: High-deductible plan structures shift more cost to employees and reduce employer-side claim frequency
• Group size: Smaller groups have higher statistical variance and therefore carry less favorable stop-loss terms

One of the most important questions to ask when evaluating a self-funded arrangement: who is setting the expected claims projection that drives the aggregate attachment point? A conservative projection that understates your expected claims creates an artificially low aggregate attachment — you'd hit the stop-loss threshold too easily, and the carrier will price future renewals upward to compensate. An aggressive projection that overstates expected claims sets the bar too high, leaving you with significant unprotected exposure.

Credible TPAs use data from your prior carrier's claims reports, national benchmarks from databases like Truven MarketScan or Milliman MedInsight, and your group's demographic profile. Ask for the actuarial assumptions behind any projection you receive before committing to a plan design.

What Stop-Loss Coverage Actually Costs

Stop-loss premiums are a separate line item from your plan's TPA fees and network access costs. Based on data from SIIA and Milliman's annual stop-loss benchmarking surveys:

• Specific stop-loss: $30 to $90 per employee per month, depending on deductible level and group risk profile
• Aggregate stop-loss: $5 to $20 per employee per month as an add-on to specific stop-loss
• Combined specific + aggregate: $40 to $120 per employee per month for most 30–150 employee groups

To put this in context: if you're paying $1,600 per employee per month in a fully-funded plan, and a self-funded arrangement (including TPA fees, network costs, and stop-loss coverage) comes to $1,380 per employee per month, you're saving $220 per employee per month — or $158,400 per year for a 60-person company. Even in a modestly challenging claims year, that margin often protects the economic argument for self-funding.

Stop-loss premiums are also subject to annual renewal, and carriers will reprice based on your claims experience. If your group has a bad year, expect stop-loss renewals to reflect that. The benefit of working with a PEO or multiemployer trust is that your individual company's difficult year gets absorbed into a much larger risk pool, smoothing stop-loss pricing volatility significantly.

How PEOs Handle Stop-Loss Differently

If you're exploring a PEO arrangement as an alternative to a standalone self-funded plan, the stop-loss mechanics work quite differently — and often more favorably for smaller employers.

Most PEOs operate under a multiemployer trust (MET) structure, where dozens or hundreds of employer groups are pooled together under a single master health plan. The PEO purchases stop-loss protection at the trust level, not at the individual employer level. Because the trust may cover 10,000 to 50,000+ enrolled lives, it qualifies for large-group stop-loss pricing — significantly cheaper and more stable than what a 50-person standalone employer would pay.

This pooling effect has several practical advantages:

• One high-cost claimant in your company doesn't reprice your stop-loss at the next renewal — your loss experience is diluted across the entire trust pool
• The PEO's actuarial team sets attachment points across the full pool, rather than using your specific group's limited claims history
• The PEO typically locks stop-loss terms for participating employers at consistent rates, reducing year-over-year renewal volatility

The trade-off is control: in a standalone self-funded plan, you have more visibility into your claims data and can make plan design changes independently. In a PEO's trust arrangement, you're subject to the trust's plan design rules — though most PEOs offer several tier options with varying coverage levels and member cost-sharing.

Is Self-Funding with Stop-Loss Right for Your Company?

Self-funded plans with stop-loss coverage aren't the right fit for every employer. Here's an honest decision framework based on group size, claims history, and financial capacity:

Factors That Favor Self-Funding

• 30+ enrolled employees (smaller groups have insufficient statistical mass for stable self-funded projections)
• Two or more years of clean claims history with a current carrier
• Workforce with favorable demographics — younger, lower-risk employee population
• Cash reserves sufficient to cover 3–6 months of expected claims before stop-loss reimbursement arrives (stop-loss carriers reimburse after the deductible is crossed, not in real time)
• Benefits advisor experienced in self-funded plan design and stop-loss placement

Factors That Favor Staying Fully-Funded or Joining a PEO Trust

• Fewer than 25–30 enrolled employees (claims variance too high for stable self-funding)
• Recent high-cost claimants or known future high-cost conditions in your workforce (pending surgery, chronic condition management, family planning)
• Limited cash reserves — stop-loss reimbursements aren't instantaneous, and cash flow management matters
• Industry with unpredictable health claims patterns (hospitality, construction, staffing with high turnover)

For employers in the 20–40 employee range who want the cost advantages of risk-sharing without the cash flow exposure of a standalone self-funded plan, a PEO's multiemployer trust often provides the best of both worlds: lower effective rates, stable renewals, and stop-loss protection embedded in the trust structure at large-group pricing.

Key Questions to Ask Before Moving to a Self-Funded Plan

Whether you're evaluating a standalone self-funded arrangement or a PEO trust, these questions will separate credible advisors from those who are simply pitching a product:

• What is the specific deductible, and how was it set? Ask for the actuarial logic, not just the number.
• Who is the stop-loss carrier? Ratings and claims-paying history matter. Ask for an A.M. Best rating — look for A- or better.
• What is the aggregate attachment point as a percentage of expected claims? 125% is standard; anything over 130% provides weaker protection.
• Is the stop-loss coverage on a paid basis or an incurred/paid basis? Incurred/paid contracts provide better coverage continuity across plan years.
• What is the run-out provision? This determines how long after the plan year ends the stop-loss carrier will pay claims that were incurred during the plan year.
• How does the TPA handle stop-loss reimbursement cash flow? Some TPAs advance reimbursements to maintain plan cash flow; others do not.

The answers to these questions will tell you more about whether a self-funded arrangement is well-structured than the projected monthly savings number alone.

Frequently Asked Questions

What is the difference between specific and aggregate stop-loss coverage?

Specific stop-loss covers individual catastrophic claims — if one employee's medical costs exceed the per-person deductible you've chosen, the stop-loss carrier reimburses the excess. Aggregate stop-loss covers your entire workforce — if total plan claims exceed 125% (or your contract threshold) of projected annual claims, the carrier reimburses the excess above that attachment point. Most self-funded plans carry both types simultaneously for complete protection.

How much does stop-loss coverage cost per employee?

Stop-loss premiums typically range from $40 to $120 per employee per month, depending on your group's size, demographics, deductible level, and claims history. Employers who join PEO trust arrangements often pay less because stop-loss is priced across a much larger pooled risk group rather than based on your specific company's individual profile.

Can a smaller employer with under 30 employees use a self-funded plan with stop-loss coverage?

Technically yes, but the economics are less favorable below 30 employees. Smaller groups have higher claims variance — a single challenging claims year can skew projections significantly, and stop-loss carriers price that uncertainty into their premiums. For employers with 20–30 employees, a PEO's multiemployer trust arrangement typically delivers better cost stability because the risk is pooled across a much larger population than any standalone small group could achieve independently.

What happens when a stop-loss claim is filed?

When an individual employee's claims cross the specific deductible, your TPA compiles the claim documentation and submits it to the stop-loss carrier. Most carriers process reimbursements within 30 to 60 days of receiving a complete claim package. Until reimbursement arrives, your plan cash account carries the full liability — which is why having adequate cash flow reserves is an important consideration when evaluating whether self-funding is the right move for your company.

Does stop-loss coverage renew automatically each year?

No. Stop-loss coverage is typically a one-year contract, and the carrier prices the renewal based on your group's claims experience during the prior year. A year with significant stop-loss claims will generally result in a higher renewal premium or, in severe cases, exclusions or carve-outs for specific high-cost conditions. This is one reason employers value PEO trust arrangements — renewal pricing is based on the full trust pool, not your individual company's single claims year.

How do I know if my current benefits advisor has experience with stop-loss programs?

Ask them directly: "Walk me through how you'd structure specific and aggregate stop-loss for our group, and name the three carriers you use most frequently." A credible advisor can explain the actuarial basis for the deductible recommendation, describe the carrier's claims-paying history, and differentiate between incurred/paid and paid-only contract forms. If they can't answer those questions fluently, look for an advisor who specializes in self-funded plan design and stop-loss placement.

References

1. Kaiser Family Foundation. (2023). Employer Health Benefits Survey 2023. San Francisco: KFF.
2. SIIA. (2023). Stop-Loss Market Survey. Simpsonville, SC: Self-Insured Institute of America.
3. Milliman. (2023). 2023 Milliman Medical Index and Stop-Loss Benchmarking Report. Seattle: Milliman, Inc.
4. AHIP. (2022). Self-Insured Health Plans: A Competitive Alternative to Fully-Funded Group Coverage. Washington, DC: AHIP.
5. Sun Life Financial. (2023). Stop-Loss Market Survey: Industry Trends and Pricing Analysis.
6. International Foundation of Employee Benefit Plans. (2023). Employee Benefits Survey. Brookfield, WI: IFEBP.