One of the most consequential rules in American health insurance law: ACA marketplace plans cannot turn you down, charge you more, or exclude treatment for a health condition you had before you enrolled. This protection applies whether your condition is cancer, diabetes, asthma, heart disease, a prior surgery, or anything else in your medical history.
This guide explains exactly what the law requires, which plan types are covered by the rule, and the one major loophole you need to know: short-term limited-duration plans are NOT subject to this protection. If you're evaluating whether to enroll, see can I buy ACA outside open enrollment and does the ACA cover mental health.
Coverage Breakdown
What the Law Actually Says: The Preexisting Condition Prohibition
Section 1201 of the Patient Protection and Affordable Care Act (Pub. L. 111-148, signed March 23, 2010) added Section 2704 to the Public Health Service Act, now codified at 42 U.S.C. 300gg-3. It reads: 'A group health plan and a health insurance issuer offering group or individual health insurance coverage may not impose any preexisting condition exclusion with respect to such plan or coverage.' This rule took full effect January 1, 2014.
The prohibition has three components insurers cannot do: (1) deny enrollment based on a preexisting condition, (2) charge higher premiums because of health status or medical history, and (3) impose waiting periods or benefit exclusions for a preexisting condition. Before this law, an insurer could legally refuse to cover your cancer treatment because you had cancer before you enrolled.
- Cancer (any type, any stage)
- Diabetes (Type 1 or Type 2)
- Heart disease, hypertension
- Asthma, COPD, other respiratory conditions
- Mental health diagnoses (depression, bipolar, anxiety)
- HIV/AIDS, hepatitis
- Pregnancy (insurers cannot treat a prior pregnancy as a preexisting condition)
- Genetic information, cannot be treated as a preexisting condition absent an actual diagnosis
The 10 Essential Health Benefits: What ACA Plans Must Cover
Beyond banning preexisting condition exclusions, ACA marketplace plans must cover the 10 Essential Health Benefits (EHBs). This matters for people with preexisting conditions because insurers cannot design a plan that technically covers you but excludes the specific treatments your condition requires. Mental health parity rules also apply — see does the ACA cover mental health.
- Ambulatory patient services (outpatient care)
- Emergency services
- Hospitalization
- Maternity and newborn care
- Mental health and substance use disorder services
- 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
The Major Loophole: Short-Term Plans Are NOT Protected
Short-term limited-duration (STLD) plans are explicitly excluded from the definition of 'individual health insurance coverage' under the Public Health Service Act. That means STLD plans are not required to cover preexisting conditions, not required to cover the 10 essential health benefits, and can deny your claim after the fact by investigating whether a condition predated your enrollment.
Federal rules finalized in 2024 cap STLD plans at 4 months total duration including renewals. But even at 4 months, these plans can leave you with an uncovered claim in the middle of cancer treatment if the insurer determines the cancer is a preexisting condition. If you have a chronic illness, significant medical history, or are currently in treatment, avoid STLD plans entirely.
2026 Enrollment: The Subsidy Cliff Has Returned
The preexisting condition protections are permanent and unchanged for 2026. However, 2026 brings a significant affordability change: the enhanced premium tax credits from the American Rescue Plan Act (ARPA) and the Inflation Reduction Act (IRA) expired December 31, 2025. The subsidy cliff is back. Households earning more than 400% of the 2025 federal poverty level ($128,600 for a family of four) no longer qualify for marketplace subsidies in 2026, regardless of what percentage of their income the premium represents.
If your income is above that threshold and you have preexisting conditions, you still have full ACA protections, but you will pay full unsubsidized premiums. Check the ACA screener to confirm your 2026 subsidy eligibility before assuming your costs have not changed.
If You Cannot Afford a Marketplace Plan: Other Options
The preexisting condition protections are strongest in ACA marketplace plans, but cost may still be a barrier in 2026. Three main alternatives exist for people who cannot afford marketplace premiums.
Frequently Asked Questions
Can an ACA marketplace plan deny me coverage because of a preexisting condition?
No. Under 42 U.S.C. 300gg-3, ACA marketplace plans cannot deny enrollment, charge higher premiums, or exclude treatment for any condition that existed before your coverage began. This rule has applied to all individual and small-group marketplace plans since January 1, 2014.
What counts as a preexisting condition under the ACA?
Any health condition you had before your coverage start date is a preexisting condition. Examples include cancer, diabetes, heart disease, asthma, mental health diagnoses, HIV, hepatitis, prior pregnancies, and past surgeries. Even a condition you were not diagnosed with but had symptoms of can qualify. Genetic information alone (without a diagnosis) cannot be treated as a preexisting condition.
Do short-term health plans cover preexisting conditions?
No. Short-term limited-duration (STLD) plans are not ACA-compliant and are legally allowed to deny coverage, exclude benefits, or rescind claims for preexisting conditions. Federal rules cap STLD plans at 4 months total in 2026. If you have chronic conditions or ongoing treatment, avoid these plans entirely and use an ACA marketplace plan instead.
Can an insurance company charge me more because I am sick?
No, on ACA marketplace plans. Insurers selling marketplace plans can only vary premiums based on age (up to a 3-to-1 ratio), geographic area, tobacco use (up to 1.5-to-1), and whether a plan covers individuals or a family. Health status and medical history cannot affect your premium on ACA-compliant plans.
I missed open enrollment. Can I still enroll if I have a preexisting condition?
You can enroll during a Special Enrollment Period (SEP) if you have a qualifying life event: losing other coverage, getting married, having a baby, moving to a new coverage area, gaining citizenship, and several others. Outside a SEP or open enrollment, you cannot enroll in a marketplace plan regardless of your medical history. Medicaid is open year-round with no enrollment windows.
Are preexisting condition protections at risk of being eliminated?
As of 2026, 42 U.S.C. 300gg-3 remains fully in effect. Prior legal challenges (including Texas v. United States) did not overturn this provision. Congress has not passed legislation repealing it. However, legislative or judicial changes are always possible. The most current status is on healthcare.gov.
Does Medicaid also cover preexisting conditions?
Yes. Medicaid has never allowed preexisting condition exclusions. Medicaid covers all medically necessary services for enrolled members regardless of any conditions they had before enrollment. As of 2026, 40 states plus DC have expanded Medicaid to cover adults earning up to 138% of the federal poverty level (about $22,025 for an individual).
How does the 2026 subsidy cliff affect people with preexisting conditions?
The preexisting condition protections are unchanged in 2026. But the enhanced premium tax credits from ARPA and the IRA expired December 31, 2025. Households earning more than 400% of the 2025 FPL no longer qualify for marketplace subsidies in 2026. This means some people with preexisting conditions who relied on enhanced subsidies now face significantly higher unsubsidized premiums. Use the ACA screener to check your 2026 subsidy status.
