Essential Health Benefits Under the ACA
The Affordable Care Act established a floor of required coverage — called Essential Health Benefits — that most individual and small-group health insurance plans must include. These requirements directly affect plan design, premium calculations, and the legal exposure of insurers and employers. Understanding how EHB rules work clarifies what plans must cover, which markets are regulated, and where coverage gaps remain lawful.
Definition and Scope
Essential Health Benefits (EHB) are a defined set of health care services that non-grandfathered individual and small-group insurance plans sold inside and outside the Health Insurance Marketplace must cover. The requirement is codified at 42 U.S.C. § 18022, a provision of the Affordable Care Act enacted in 2010.
The U.S. Department of Health and Human Services (HHS) is the primary federal agency with rulemaking authority over EHB standards. HHS implements the EHB framework primarily through regulations in 45 C.F.R. Part 156, which specifies how states select benchmark plans and what substitution rules apply.
The statute divides EHB into 10 benefit categories:
- Ambulatory patient services
- Emergency services
- Hospitalization
- Maternity and newborn care
- Mental health and substance use disorder services, including behavioral health treatment
- Prescription drugs
- Rehabilitative and habilitative services and devices
- Laboratory services
- Preventive and wellness services and chronic disease management
- Pediatric services, including oral and vision care
Each state selects an EHB benchmark plan — historically one of the 3 largest small-group plans in the state — against which all covered plans in that market measure compliance. This benchmark approach means EHB-required services differ state by state within the 10-category floor. The broader regulatory context for ACA sets out how HHS, the IRS, and the Department of Labor divide enforcement authority across these overlapping mandates.
Large-group and self-funded plans are not required to cover EHBs, but they cannot impose annual or lifetime dollar limits on EHB-equivalent services if they choose to cover those services (45 C.F.R. § 147.126).
How It Works
Compliance with EHB requirements follows a benchmark-and-substitution framework. Under 45 C.F.R. § 156.115, a plan satisfies the EHB mandate by covering benefits substantially equal to those in the state's benchmark plan across all 10 statutory categories.
Insurers may substitute benefits within a category — replacing one specific service with another of equal or greater actuarial value — but cannot substitute across categories. A plan may not reduce the mental health category to fund an expansion of prescription drug coverage. HHS guidance on substitution is detailed in the annual Notice of Benefit and Payment Parameters, published each year in the Federal Register.
Quantitative limits matter: plans may not impose annual dollar limits on EHB coverage, and cost-sharing must comply with the annual limits set under 42 U.S.C. § 18022(c). For plan years beginning in 2024, the out-of-pocket maximum for self-only coverage is $9,450 (CMS, Notice of Benefit and Payment Parameters for 2024).
Prescription drug coverage within EHB must include at least 1 drug in every United States Pharmacopeia (USP) category and class, and plans must include at least the same number of drugs in each category as the benchmark plan (45 C.F.R. § 156.122).
Common Scenarios
Individual and small-group market plans: A carrier selling a Bronze-tier plan on Healthcare.gov must cover all 10 EHB categories against the applicable state benchmark. Metal tier selection — Bronze, Silver, Gold, or Platinum — affects the actuarial value of cost-sharing, not the breadth of covered services. Coverage breadth is fixed by EHB rules while cost-sharing levels vary by tier. The ACA plan design guide expands on how benefit design intersects with actuarial value requirements.
Maternity and newborn care: Prior to the ACA, individual market plans in most states excluded maternity coverage or sold it as a costly rider. EHB mandate category 4 (maternity and newborn care) eliminated that practice for covered markets. A plan may not exclude prenatal visits, delivery, or newborn care from an individual market policy.
Mental health parity interaction: Category 5 (mental health and substance use disorder) operates alongside the Mental Health Parity and Addiction Equity Act (MHPAEA). A plan must cover these services as EHB and may not impose treatment limitations — such as visit caps — that are more restrictive than those applied to comparable medical or surgical benefits (29 U.S.C. § 1185a).
Self-funded employer plans: A self-funded plan is exempt from the EHB coverage mandate but must not impose annual or lifetime dollar limits on any benefits it covers that are EHB-equivalent. An employer with a self-funded plan that covers hospital services cannot cap hospital benefits at $500,000 per year. This prohibition applies regardless of group size.
Grandfathered plans: Plans that maintained continuous enrollment since March 23, 2010 and have not made specified significant changes may retain grandfathered status and are exempt from EHB requirements. The share of enrollment in grandfathered plans has declined substantially since 2010 as employers updated plan terms.
Decision Boundaries
EHB obligations apply or do not apply based on three primary classification variables: market segment, plan funding type, and grandfathered status.
| Variable | EHB Coverage Mandate Applies? | Dollar Limit Prohibition Applies? |
|---|---|---|
| Individual market (non-grandfathered) | Yes | Yes |
| Small-group market (non-grandfathered) | Yes | Yes |
| Large-group fully insured | No | Yes (for covered EHB services) |
| Self-funded employer plan | No | Yes (for covered EHB services) |
| Grandfathered individual/small-group | No | No |
| Excepted benefits (standalone dental/vision) | No | No |
A plan's obligation to cover EHB also terminates if it qualifies as an excepted benefit under 45 C.F.R. § 148.220. Standalone dental plans, standalone vision plans, and short-term limited-duration plans fall outside the EHB mandate — though short-term plans carry their own regulatory restrictions at the federal level.
State variation creates an additional decision boundary. A state may require a benchmark plan that exceeds federal minimums. If a state mandates coverage for services beyond the 10 federal categories, those additional mandates bind plans within that state regardless of the federal floor. Employers operating across state lines should consult state-level ACA implementation differences to identify where benchmark plans diverge.
Finally, determining whether a plan alteration causes the loss of grandfathered status — which would trigger full EHB applicability — requires analysis against the specific change thresholds in 45 C.F.R. § 147.140. Changes such as eliminating benefits for a condition, significantly raising cost-sharing, or reducing employer contribution percentages beyond defined thresholds each independently trigger loss of grandfathered status. The full range of ACA coverage rules and how they layer together is documented in the ACA topic index.
References
- 42 U.S.C. § 18022 — Essential Health Benefits (U.S. House Office of the Law Revision Counsel)
- 45 C.F.R. Part 156 — Health Insurance Issuer Standards (eCFR, HHS)
- 45 C.F.R. § 147.126 — Prohibition on Annual and Lifetime Dollar Limits (eCFR)
- 45 C.F.R. § 147.140 — Grandfathered Health Plans (eCFR)
- [CMS Notice
The law belongs to the people. Georgia v. Public.Resource.Org, 590 U.S. (2020)