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Group captives for medical stop-loss: how employer health captives work

How a group captive layers into medical stop-loss for self-funded employers, what members put up and share, the trade-offs, and what to check before joining.

4BusinessInsurance · Published October 10, 2026

A group captive for medical stop-loss is an insurer owned by the employers it covers. Each member runs its own self-funded health plan, and the captive takes a slice of the large-claim risk that would otherwise sit entirely with a commercial stop-loss carrier, with members sharing the underwriting result. It suits mid-sized employers who already self-fund, expect their claims to be stable, and are willing to share an outcome with other employers over several years.

The layers: where the captive sits

A self-funded employer pays claims from its own money up to a point, and stop-loss insurance pays above it. A medical group captive usually inserts a layer between the two.

  1. Employer's retention. The employer pays all claims up to its specific attachment point per person (for example, a per-person deductible chosen with the broker), and up to an aggregate level across the whole plan.
  2. Captive layer. Claims above the member's retention up to a stated amount per person are paid from the captive, which is funded by member premiums and capital contributions.
  3. Excess layer. Above the captive's layer, a commercial stop-loss carrier or reinsurer pays, typically with a lower attachment point than the member could buy alone.

The captive itself does not usually sell directly to members. A licensed carrier issues the stop-loss policy to the employer, then cedes part of the risk to the captive through reinsurance. That is a fronting arrangement, and the fronting carrier charges a fee and often requires collateral from the captive. Because ordinary stop-loss insurance is not health insurance and does not pay claims to employees, the employer's obligations under the plan, including claims payment and ERISA fiduciary duties, stay with the employer.

Why employers use them

  • Share in underwriting profit. In traditional stop-loss, the premium and the loss ratio belong to the carrier. In a captive, favorable claims experience across the group can come back to members as dividends or reduced future contributions.
  • Pooled mid-layer volatility. One employee with a $900,000 claim will dominate a 150-employee plan's year. Spreading the layer over many employers smooths that.
  • Reduced lasering. A laser is an individual-specific higher deductible a stop-loss carrier sets for a known high-cost person. Some captives are built to take on members without lasers, though the program may screen members at entry.
  • Incentive to manage cost. Members usually commit to data sharing, care management, pharmacy management and a claims-review process, because every member's results affect everyone's.

What members give up or take on

  • Shared results. A bad year for the group, or for a large account in it, can mean extra assessments or reduced returns. Ask how that is capped.
  • Capital and collateral. Members typically contribute to the captive's capital and may post collateral, often a letter of credit, held by the fronting carrier. This is cash flow you do not have in a conventional stop-loss placement.
  • Multi-year commitment. Captives work through time; exit terms matter. Ask what happens to your share of reserves and any accrued dividends if you leave, and whether you stay liable for losses from the years you were in.
  • Governance. A member usually has a seat or vote on a board or committee. That is time, and some responsibility.
  • Complexity. There is a captive manager, an actuary, a fronting carrier, the TPA and your broker. Understand who is paid what.

A worked example (hypothetical)

Say a 220-employee distributor in Pennsylvania self-funds with a $125,000 specific retention and pays a conventional stop-loss premium. Its broker proposes a group captive: the distributor keeps the $125,000 retention, the captive takes losses from $125,000 to $250,000 per person, and a commercial reinsurer sits above $250,000. The employer posts a capital contribution and a letter of credit. In a year with three claims between $125,000 and $250,000, the captive pays the excess portion, funded by the pool. If the whole group runs better than expected, the captive returns some surplus; if it runs worse, the employer may face a premium adjustment. The decision is not whether the quoted premium is lower this year, but whether a three- to five-year view of the layer's loss history and the exit terms make sense. The deductible and retention break-even calculator is a good place to test retention levels.

Regulation and tax

Due diligence checklist

  1. Ask for the captive's loss history by layer for the last five years, and the actuary's report.
  2. Get the exact definitions of a covered claim, run-in and run-out terms, and any waiting period before the captive pays.
  3. Find out how new members are underwritten and whether lasers or exclusions are applied.
  4. Clarify capital contributions, collateral, and whether either is returned on exit.
  5. Read the governance documents: voting, assessment caps, how a member can be removed.
  6. Identify who holds the fronting relationship and who is paid fees; compare to a conventional stop-loss insurance placement at the same retention.
  7. Confirm the captive's AM Best or other rating, if any, and the quality of the reinsurer above it.
  8. Check whether your TPA supports the data feeds the captive requires.

If a captive is not a fit, level-funded health plans: how they work, who they suit and the catches bundle stop-loss into a fixed monthly payment, and Is a captive right for your business? A feasibility checklist is a broader feasibility checklist.

Key takeaways

  • A medical stop-loss captive takes a middle layer of per-person claims between the employer's retention and a commercial excess layer, with members sharing results.
  • It is usually reached through a fronting stop-loss policy, and the employer remains fully responsible for the self-funded plan.
  • Expect capital, collateral, a multi-year commitment and shared-loss exposure in return for a chance at returned surplus.
  • Diligence centers on loss history, exit terms, governance and the tax position, not just the first-year quote.

Terms used in this guide

Captive insurance company A licensed insurer owned by the business or group it insures, formed to underwrite their own risks rather than buying all coverage from outside insurers. Stop-loss insurance Insurance that reimburses an employer with a self-funded health plan when one person's claims, or the plan's total claims, pass a set dollar level. Self-funded health plan A group health plan where the employer pays employees' claims itself rather than paying an insurer premiums, usually backed by stop-loss insurance. Attachment point The loss amount at which an excess, umbrella or reinsurance layer starts paying, normally the top of the underlying limits or retention beneath it. Third-party administrator (TPA) An outside firm hired to run claims and administration for a self-funded plan, captive or self-insured program without taking on the insurance risk. Fronting An arrangement where a licensed insurer issues the policy but passes most or all of the risk to a captive or reinsurer, for a fee.

Related tools

Deductible and retention break-even calculator Compares two deductible or retention options by expected annual cost, finds the claim frequency where they cost the same, and shows what a bad year would cost.

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