Short-Term Health Plans vs ACA Marketplace: What Each Actually Covers When You Get Sick

A 41-year-old consultant in Houston dropped her COBRA for a $127 monthly short-term medical plan, tore her ACL three months later in a pickup basketball game, and walked away with a $38,400 bill the short-term plan refused to cover because the insurer ruled her knee pain from a 2023 urgent care visit a pre-existing condition. She had been paying $612 a month on COBRA after leaving her agency job. The short-term plan saved her $485 a month, roughly $5,800 over a year if she kept it. The surgery, MRI, anesthesia, surgery center, and physical therapy totaled $38,400. The insurer pulled her records, found the 2023 urgent care note mentioning “mild knee discomfort,” and denied the claim under the pre-existing condition exclusion. She could have had a silver ACA marketplace plan for $218 a month after premium tax credits, with a $3,200 out-of-pocket maximum and no pre-existing condition underwriting. She would have paid $3,200 for the surgery instead of $38,400.

These Are Not the Same Product

ACA marketplace plans and short-term medical plans are sold in the same place, advertised in the same search results, and pitched with similar language about “affordable coverage.” They are not the same product. ACA plans operate under the Affordable Care Act rules. They must cover the ten essential health benefits, cannot exclude pre-existing conditions, cannot cap annual or lifetime benefits, and must cap your out-of-pocket exposure each year. The premium reflects those rules.

Short-term medical plans, sometimes called short-term limited duration insurance, operate under a separate regulatory regime that was expanded in 2018 and tightened again in 2024. They are medically underwritten, which means the insurer reviews your medical history and either denies coverage, excludes specific conditions, or charges a higher rate. They can and do exclude pre-existing conditions for the life of the policy. They are not required to cover maternity, mental health, prescription drugs, or preventive care. They can impose annual and per-benefit caps. They can refuse to renew you the moment you file a significant claim. None of this is buried in a footnote. It is the product.

The premium difference reflects what each plan actually does. A short-term plan is cheaper because it covers less and can exit when the cost rises. An ACA plan is more expensive up front because it cannot.

Four Differences That Matter When You Get Sick

The four places short-term and ACA plans diverge are the four places a medical event exposes whichever gap your plan has.

• Pre-existing conditions. ACA plans cannot underwrite or exclude anything in your medical history. Short-term plans can exclude any condition that was diagnosed, treated, or even mentioned in a record during a lookback period, typically 12 to 60 months. The Houston consultant’s knee pain from two years earlier, documented in a single urgent care visit, was enough to kill the ACL claim.
• Essential health benefits. ACA plans must cover ten categories, including maternity, mental health, prescriptions, and preventive care. Short-term plans can cover none of them. Many short-term policies explicitly exclude maternity, which is why a 30-year-old woman trying to start a family almost always pays more for an ACA plan and almost always comes out ahead.
• Annual and lifetime caps. ACA plans cannot impose them. Short-term plans cap total payouts at $1M to $2M, with tight sub-caps on specific categories, often $5,000 to $10,000 on rehabilitation and therapy per injury. A knee surgery plus six months of physical therapy alone can clear the per-injury rehab cap on a short-term plan, leaving the insured holding the rest.
• Out-of-pocket maximums. ACA plans cap your out-of-pocket exposure annually, typically between $3,000 and $9,450 for individual coverage. Short-term plans do not. Once the policy’s sub-caps kick in, your exposure is whatever the hospital bills minus whatever the insurer agreed to pay, and the rest is yours.

Each of those differences is individually survivable if you are healthy and young. Stacked together, they turn a short-term plan into a coverage product that looks like insurance on paper and behaves like no insurance at all during an actual claim.

When Short-Term Plans Actually Make Sense

There is a narrow band where short-term coverage is the right call. A healthy adult under 30 with no ongoing medications and no medical history, bridging 30 to 60 days between an old employer plan ending and a new employer plan starting, can reasonably carry short-term coverage for catastrophic risk without paying ACA premiums for a month. The math works because the exposure window is short, the medical history is clean, and the odds of a claim that hits the short-term plan’s sub-caps are genuinely low.

Outside that band, the math breaks. Anyone with a chronic condition, anyone who needs regular prescriptions, anyone over 40, anyone planning a pregnancy, anyone covering a family, anyone with a mental health diagnosis, anyone whose medical records include the words “history of,” is paying for a product that will use one of those notes to deny a claim. The premium savings do not survive contact with one real bill.

Premium Tax Credits Most People Qualify For and Miss

The reason ACA marketplace plans feel unaffordable is that most people searching for a plan do not enter their income into the subsidy calculator before they compare premiums. The sticker price of a silver plan can be $600 to $900 per month. The actual post-subsidy price for a self-employed worker earning $65,000 is often $180 to $280 per month, depending on state and age. Premium tax credits are built into the checkout flow on healthcare.gov and most state exchanges, and they apply automatically to the monthly premium rather than showing up as a tax refund.

The 400 percent of federal poverty line cliff, which used to cut off subsidies abruptly for middle-income households, was removed through 2025 under the Inflation Reduction Act extension. That means a single person earning $90,000 in a high-cost state can still qualify for partial subsidies, and a family of four earning $150,000 often qualifies for meaningful help. Anyone shopping short-term as a cost play needs to run the ACA number with the real subsidy applied before deciding. It is almost always cheaper than it looks.

Questions to Ask Before You Enroll

• What is my income, and have I run the ACA marketplace subsidy calculator at healthcare.gov with that number?
• Does the short-term plan I am considering have a pre-existing condition lookback period, and if so, how many months or years does it cover?
• What is the annual and per-injury cap on rehabilitation, therapy, and prescription drugs on the short-term plan?
• Does the plan cover maternity, mental health, and prescriptions, or are those excluded?
• If I file a significant claim, can the insurer refuse to renew the policy at the end of the term?

A quick side-by-side with the real numbers on premiums, deductibles, and out-of-pocket maximums will usually resolve the decision in under 15 minutes. Running the subsidy calculator first is the part most people skip, and it is the part that changes the math.

The Cheapest Coverage Is Not the Cheapest Bill

The Houston consultant finished the year roughly $38,400 out of pocket on a plan that saved her $485 a month. Net, she lost $32,580 compared to staying on COBRA, and roughly $35,000 compared to the ACA plan she would have qualified for. The monthly premium was the wrong metric to optimize, and the short-term plan was the wrong product. She moved to a silver ACA plan at the next open enrollment, pays $218 a month, and had her physical therapy refills covered at a $30 copay. Before you drop a more expensive plan for a cheaper one, read the actual plan documents side by side and run the ACA subsidy calculator with your real income first.