The core difference: who carries the claims risk
In a fully insured plan, the employer pays a fixed premium and an insurance carrier pays the claims. Good year or bad, the premium is spent — and next year's renewal quietly reflects last year's experience plus trend plus margin.
In a self-funded (self-insured) plan, the employer pays its own employees' claims from plan assets, usually hiring a third-party administrator to process them and buying stop-loss insurance to cap catastrophic exposure. The employer keeps the difference in a good claims year and absorbs (up to the stop-loss ceiling) a bad one.
This isn't a niche structure. Federal survey data has long shown that around two-thirds of covered U.S. workers are in plans that are at least partially self-funded — it is the default for large employers and increasingly common in the mid-market through level-funded arrangements.
What each model means in practice
| Dimension | Fully insured | Self-funded |
|---|---|---|
| Claims risk | Carrier | Employer (capped by stop-loss) |
| Good claims year | Carrier keeps the surplus | Employer keeps the surplus |
| Regulation | State insurance mandates + ACA | ERISA framework (federal), preempting most state benefit mandates |
| Premium taxes | Built into premium | Largely avoided on the self-funded portion |
| Claims data access | Often limited | The employer's own data |
| Plan design flexibility | Carrier's filed products | Broad — the employer designs the plan |
| Cash flow | Fixed monthly premium | Pay claims as incurred; more variable |
Two of those rows do most of the strategic work. Data access means a self-funded employer can actually see where its money goes — which conditions, which facilities, which avoidable utilization. Design flexibility means it can act on what it sees, adding targeted benefits that a filed, fully insured product wouldn't offer.
Where the savings actually come from
Self-funding isn't automatically cheaper — it removes the carrier's risk margin, premium tax on the funded portion, and some administrative load, but it exposes the employer to claims volatility. The durable savings come from what self-funding enables:
- Cost containment programs with a direct payback. When the plan pays its own claims, every avoided ER visit is the employer's savings, not the carrier's. That changes the ROI on everything from care navigation to redirecting avoidable ER visits.
- Benefit additions that reduce claims. A fully insured employer who adds a telehealth and in-home diagnostics benefit is improving access; a self-funded employer doing the same is also cutting its own claims spend — the ROI calculator shows how that math works per covered employee.
- Contract scrutiny. PBM terms, network arrangements, and administrative fees are all negotiable and auditable when they're your contracts.
The flip side: volatility management is not optional. Stop-loss placement, adequate reserves, and honest actuarial projections are what make the structure safe — which is why the supporting cast (TPA, stop-loss carrier, broker or consultant) matters so much.
Which employers should consider self-funding
The traditional wisdom said self-funding starts at several hundred employees. The market has moved: level-funded plans now package self-funding mechanics — with tight stop-loss protection and fixed monthly payments — for groups well under a hundred lives, giving smaller employers a first step into claims ownership.
Signals that self-funding (or level-funding) deserves a look:
- Renewals keep climbing with no visibility into why
- A workforce that's stable and, on average, healthier than the book of business your carrier prices against
- Appetite to actually manage the plan — data review, targeted benefits, vendor accountability
- Frustration that valuable benefits (direct primary care, on-site or in-home care models) don't fit the carrier's filed products
Employers weighing the move should pressure-test the supporting pieces first: what a TPA does, how stop-loss insurance works, and how employers reduce claims spend once they own it.