In insurance, ASO stands for Administrative Services Only, and it describes a self-funded health plan where the employer pays employee medical claims out of its own money and hires a third-party administrator (TPA) to handle the operational work. The TPA processes claims, manages the provider network, and answers member questions, but it never becomes financially responsible for paying claims. That responsibility, and the risk that goes with it, stays with the employer. ASO plans are governed primarily by federal law under ERISA, which exempts them from most state insurance regulation while imposing its own rules on reporting, fiduciary conduct, and claims handling.
The label is worth reading literally. The administrator is providing services only. It is not providing insurance.
How ASO Differs From a Fully Insured Plan
In a fully insured plan, the employer pays a set premium to an insurance carrier, and the carrier assumes the financial risk of covering employee claims. If claims spike in a given year, the insurer absorbs the cost. In an ASO arrangement, those roles split apart. The employer keeps the financial risk. The TPA provides administrative services for a fee and is never liable for claim payments.
That split changes the economics. Fully insured premiums build in a margin for the insurer’s profit, risk charges, and state premium taxes. Self-funded employers avoid those layers, which is the primary cost argument for going ASO. In a light-claims year, the employer’s total spending can come in well below what a fixed premium would have been. In a heavy-claims year, the opposite is true. A fully insured employer can budget a known monthly cost and stop worrying about flu season. An ASO employer needs cash reserves, stop-loss coverage, and a tolerance for month-to-month variability.
There is also a regulatory difference. Self-funded plans are exempt from state-mandated benefit requirements because ERISA preempts state insurance laws for these plans. A state law requiring coverage of a specific treatment does not apply to an ASO plan the way it applies to a fully insured policy. That gives employers more flexibility to design benefits around their actual workforce. Federal rules like ACA preventive-service coverage and mental health parity still apply, so the flexibility has limits.
Who Uses ASO Arrangements
ASO is most common among mid-size and large employers with enough employees to spread risk and enough cash flow to absorb variability. Some TPAs set minimums as low as 10 enrolled employees, but the economics generally work better for groups of 50 or more, where claims costs become more predictable year to year. Very large employers with thousands of employees can self-fund with relatively low stop-loss exposure because their claims experience is statistically stable.
Smaller employers considering the switch need to pay close attention to cash reserves. A single catastrophic claim in a 30-person group can swing total annual costs dramatically, which is why stop-loss coverage becomes non-negotiable at smaller group sizes. Employers with young, healthy workforces sometimes find ASO attractive because their actual claims run well below what a fully insured premium would assume.
What the TPA Does and What the Employer Keeps
The relationship between the employer and the TPA is set out in a written services agreement. The contract lists the specific administrative services the TPA will provide, how fees are calculated, what performance standards apply, and how any disagreements get resolved. It also makes clear, in language that separates ASO from insurance, that the TPA has no obligation to pay claims from its own funds.
Most contracts give the TPA authority to adjudicate claims against the plan document the employer has designed. The TPA decides whether a submitted claim meets the plan’s terms, calculates the payment amount, and processes the transaction. But the employer keeps control of plan design, benefit levels, and funding decisions. Changing a copay structure or adding a benefit category is the employer’s call, not the TPA’s.
TPA fees are typically charged on a per-employee-per-month basis and cover claims adjudication, network access, member services, and compliance support. Those fees are reasonably predictable. Claims cost itself is the variable piece. Most ASO employers fund a dedicated claims account on a weekly or biweekly cycle tied to the TPA’s payment schedule, and treat cash flow management as an ongoing discipline rather than a set-it-and-forget-it exercise.
Federal rules also govern how fast the TPA has to move on claims: 72 hours for urgent care claims, 15 days for pre-service claims, and 30 days for post-service claims, with possible extensions when more information is needed.1eCFR. 29 CFR 2560.503-1 Claims Procedure
Stop-Loss Insurance: The Piece That Makes ASO Workable
Stop-loss insurance is the safety net that makes self-funding realistic for most employers. It reimburses the employer when claims exceed pre-set thresholds, putting a ceiling on worst-case exposure. Two versions are standard.
- Specific stop-loss covers any single individual whose claims exceed a chosen attachment point during the plan year. The employer picks the attachment point based on its risk tolerance and budget. A lower attachment point means less exposure but a higher stop-loss premium.
- Aggregate stop-loss kicks in when total plan claims for the year exceed a percentage of expected claims, usually set around 125% of projected costs. This protects against an unusually bad year across the entire group rather than one expensive individual.
One detail regularly catches employers off guard: stop-loss reimbursement arrives after the employer has already paid the claim. The employer needs enough liquidity to cover high-cost claims upfront and then wait for the stop-loss carrier to process reimbursement. The lag can run weeks or months. Stop-loss premiums are paid separately from TPA administrative fees, and although the underlying self-funded plan is not subject to state insurance regulation, the stop-loss policy itself is.
Federal Rules That Still Apply
ERISA preempts most state insurance laws for self-funded ASO plans, but the plan is not unregulated. Several federal laws impose direct compliance obligations, and the employer bears responsibility for meeting them even when the TPA handles the day-to-day work.
ERISA Reporting and Disclosure
The plan administrator must file a Form 5500 annual return with the Department of Labor.2U.S. Department of Labor. Instructions for Form 5500 Annual Return/Report of Employee Benefit Plan The employer must also provide each participant with a Summary Plan Description explaining covered benefits, exclusions, claims procedures, and appeal rights. These documents define the legal terms of the plan and become central exhibits in any dispute over a denied claim.
ACA Requirements
ACA provisions apply to self-funded plans the same way they apply to fully insured ones. The plan must cover recommended preventive services without cost-sharing. Lifetime and annual dollar limits on essential health benefits are prohibited.3eCFR. 45 CFR 147.126 – Prohibition on Lifetime and Annual Limits Dependent children must be eligible for coverage until age 26. Pre-existing condition exclusions are not allowed. Applicable large employers that sponsor self-insured plans also have ACA reporting duties, including furnishing Form 1095-C to each full-time employee.4Internal Revenue Service. Instructions for Forms 1094-C and 1095-C
COBRA
Employers with 20 or more employees must offer COBRA continuation coverage when an employee or covered dependent loses eligibility due to job loss, reduced hours, divorce, or other qualifying events.5U.S. Department of Labor. Continuation of Health Coverage (COBRA) Notice deadlines are tight, and missing them exposes the employer to excise taxes and lawsuits.6U.S. Department of Labor. An Employers Guide to Group Health Continuation Coverage Under COBRA
Mental Health Parity
The Mental Health Parity and Addiction Equity Act requires self-funded plans that offer mental health or substance use disorder benefits to provide them on terms no more restrictive than medical and surgical benefits. Financial requirements like copays cannot exceed the levels applied to comparable medical services, and non-quantitative restrictions like prior authorization must use the same standards.7U.S. Department of Labor. Self-Compliance Tool for the Mental Health Parity and Addiction Equity Act Enforcement in this area has intensified in recent years.
No Surprises Act
The No Surprises Act applies to self-funded plans and prohibits surprise billing for emergency services, out-of-network care at in-network facilities without informed consent, and out-of-network air ambulance services. Employee cost-sharing in those situations cannot exceed the in-network amount.8CMS. No Surprises Act Overview of Key Consumer Protections
Transparency in Coverage
Since July 2022, most group health plans, including self-funded ASO plans, must publish machine-readable files on a public website disclosing in-network negotiated rates and out-of-network allowed amounts for covered services.9CMS. Use of Pricing Information Published Under the Transparency in Coverage Final Rule The TPA usually generates the files, but the employer is responsible for making sure they are published and updated.
HIPAA
Self-funded plans are covered entities under HIPAA. The employer must restrict which employees can access protected health information, maintain physical and electronic security measures, and follow breach notification procedures.
PCORI Fee and Nondiscrimination Testing
Self-funded employers pay the PCORI fee, filed on IRS Form 720, and self-funded medical plans must pass Section 105(h) nondiscrimination tests designed to prevent plans from favoring highly compensated individuals over rank-and-file employees.10Internal Revenue Service. Patient Centered Outcomes Research Trust Fund Fee Questions and Answers11Internal Revenue Service. Technical Assistance – Self-Insured Medical Reimbursement Plans Failing the tests does not disqualify the plan, but the excess benefits received by highly compensated individuals become taxable income to them.
Fiduciary Responsibility Stays With the Employer
An employer sponsoring a self-funded plan is a fiduciary under ERISA, with a legal duty to act in the best interest of plan participants and their dependents.12U.S. Department of Labor. Understanding Your Fiduciary Responsibilities Under a Group Health Plan Hiring a TPA does not transfer that liability. The employer remains responsible for monitoring the TPA’s performance, ensuring plan assets are used exclusively for participants, and making sure the plan operates according to its governing documents.
In practice, that rules out handing the plan off and looking away. If the TPA is improperly denying claims, misapplying plan terms, or charging fees that were never agreed to, the employer is on the hook for failing to catch it. Periodic audits of claims processing, fee reconciliations, and spot-checks of denied claims are the minimum expected effort. Written records of oversight and decision-making help demonstrate due diligence if a participant complains or the Department of Labor investigates. When enforcement actions do happen, the consequences can include personal liability for plan fiduciaries, required restitution to the plan, and removal of fiduciaries who breached their duties.
That is what ASO means in insurance, and why the distinction matters. The employer is not buying coverage. It is buying help running a plan it funds and legally owns.