Most health insurance mistakes do not look like mistakes when you make them. Picking the lowest premium feels sensible. Letting last year’s plan roll over feels safe. Guessing at next year’s income feels harmless. Then a bill arrives, a doctor turns out to be out of network, or the IRS asks for a subsidy back, and a ten-minute decision ends up costing thousands of dollars.
Below are the ten errors we see most often among people buying their own coverage, why each one hurts more in 2026 than it used to, and the specific step that prevents it. If you are still deciding between carriers, start with our guide to the best health insurance companies of 2026, then come back here before you click “enroll.”
Mistake 1: Shopping on premium alone
The monthly premium is the only number most people compare, and it is the least informative one. What you actually pay in a year is the premium plus the deductible, copays and coinsurance you rack up when you use care, capped by the plan’s out-of-pocket maximum. A cheap premium usually buys an expensive deductible.
According to KFF’s analysis of 2026 marketplace enrollment, the average marketplace deductible jumped to $3,786 from $2,759 the year before, an increase of $1,027 that KFF called the steepest ever. Bronze plans rose to 40 percent of all selections as shoppers chased lower premiums. The 2026 out-of-pocket maximum is $10,600 for an individual and $21,200 for a family, and for 2027 plans it rises to $12,000 and $24,000.
When you compare plans on HealthCare.gov, enter how much care you expect to use, and the site shows an estimated total yearly cost for each plan, not just the premium. Compare that figure. If you take a regular prescription or expect a procedure, a Silver or Gold plan with a higher premium often wins on total cost. Our article on Bronze, Silver, Gold and Platinum tiers walks through the math tier by tier.
The one Bronze upside people miss
If you do go Bronze, do not skip the tax break that comes with it. Starting in 2026, every Bronze and Catastrophic marketplace plan is treated as an HSA-eligible high-deductible plan, so you can put up to $4,400 (self-only) or $8,750 (family) into a health savings account, plus $1,000 if you are 55 or older. Ignoring that is a quiet way to overpay in taxes.
Mistakes 2 and 3: Skipping the provider directory and the drug list
Two plans with the same metal tier and similar premiums can have completely different networks. Marketplace plans are increasingly HMOs and EPOs, which pay nothing for out-of-network care except emergencies. If your doctor or the hospital near you is not in the network, the plan is useless for those visits no matter how good it looks on paper.
The same goes for prescriptions. Each plan has a formulary, a list of covered drugs and the tier each one sits on. A medication that costs a $10 copay on one plan can be uncovered on another.
In the KFF survey of consumer experiences with health insurance, 58 percent of insured adults said they had a problem with their insurance in the past year and 18 percent had a claim denied.
Before you enroll:
- Use the HealthCare.gov filters to add your doctors and prescriptions, so only plans that cover them appear.
- Call the doctor’s office and ask whether they accept the exact plan name, not just the insurer. A Blue Cross employer PPO and a Blue Cross marketplace HMO are different networks.
- Open the plan’s formulary PDF and search for each drug you take, including the dose and form.
If you are unsure which network structure fits you, our explainer on HMO vs PPO vs EPO vs POS plans lays out what each one allows.
Mistake 4: Picking Bronze when Silver comes with cost-sharing reductions
This is the most expensive mistake on the list for lower-income households. If your income is between 100 and 250 percent of the federal poverty level, a Silver plan bought through the marketplace comes with cost-sharing reductions (CSRs) that slash the deductible and out-of-pocket limits. A standard Silver plan covers about 70 percent of costs on average. With CSRs, the plan covers 94, 87 or 73 percent, depending on your income, while you keep paying the Silver premium. Bronze and Gold plans never get CSRs.
KFF reports that only 37 percent of 2026 enrollees took CSR plans, down from prior years, as more people fled to Bronze. Many gave up a plan that would have covered nearly everything to save a few dollars a month.
Coverage for 2026 uses the 2025 poverty guidelines ($15,650 for one person, $32,150 for a family of four). Here is where the CSR levels fall:
| Income (percent of poverty level) | Single person, 2026 coverage | Family of four, 2026 coverage | Silver plan pays (average) |
|---|---|---|---|
| 100 to 150 percent | $15,650 to $23,475 | $32,150 to $48,225 | 94 percent |
| 150 to 200 percent | $23,475 to $31,300 | $48,225 to $64,300 | 87 percent |
| 200 to 250 percent | $31,300 to $39,125 | $64,300 to $80,375 | 73 percent |
| Above 250 percent | Over $39,125 | Over $80,375 | 70 percent (no reduction) |
For 2027 coverage the 2026 guidelines apply ($15,960 single, $33,000 for four), so the brackets shift up slightly. The rule of thumb does not change: if you qualify for CSRs, Silver is almost always the right answer. The details are at HealthCare.gov’s cost-sharing reduction page.
Mistake 5: Guessing at your income
Marketplace subsidies are based on the income you expect to earn during the coverage year, not what you earned last year. When you enroll, you estimate. At tax time, the IRS compares your estimate to reality on Form 8962. If you earned more than you said, you repay some or all of the advance premium tax credit you received.
Two things make this far more dangerous in 2026. First, the enhanced subsidies expired at the end of 2025, so the subsidy cliff is back: households above 400 percent of the poverty level ($62,600 for one person, $128,600 for a family of four on 2026 coverage) get no credit at all. Second, the One Big Beautiful Bill Act eliminated the caps on how much you can be asked to repay. For tax year 2025, a single filer between 300 and 400 percent of poverty could owe back at most $1,625. From tax year 2026 onward, you repay every dollar of excess credit.
A worked example
Say a single freelancer estimates $50,000 of income for 2026. That is about 319 percent of the poverty level, which puts her in the 300 to 400 percent band. Under IRS Revenue Procedure 2025-25, her expected contribution toward the benchmark Silver plan is 9.96 percent of income, or $4,980 a year, roughly $415 a month. The marketplace pays the rest of the benchmark premium as an advance credit.
Now suppose a late-year contract pushes her actual income to $63,000. That is $400 over the cliff. Her eligibility for the credit disappears entirely, and because the repayment cap is gone, she owes back every dollar of advance credit paid on her behalf that year when she files. Under the old capped rules she would have owed $1,625 at most. Under the 2026 rules the bill is the full credit.
The fix: report income changes to the marketplace as soon as they happen so your advance credit adjusts in real time, and if you are close to the cliff, consider pre-tax retirement or HSA contributions that lower your modified adjusted gross income. Our guides on ACA subsidies in 2026 and coverage for the self-employed go deeper on both strategies.
Mistakes 6 and 7: Auto-renewing blind and missing the deadline
Auto-renewal used to be a safe default. It is not anymore, for three reasons:
- Your insurer may be gone. Aetna left every marketplace for 2026. Cigna is exiting all 11 of its individual-market states after December 31, 2026. Molina is shrinking from 14 states to 6 for 2027, and Ambetter is leaving Delaware and New Hampshire. If your carrier leaves, the exchange may map you to a different plan you never chose.
- Auto-renewal can no longer upgrade you. Under a 2025 federal rule, the marketplace cannot move a Bronze enrollee into a cost-sharing-reduction Silver plan automatically, even if you now qualify for one. You have to pick it yourself.
- Prices reshuffle every year. Benchmark Silver premiums rose an average of 26 percent for 2026. The cheapest plan in your county last year is often not the cheapest this year, and your subsidy is pegged to the new benchmark.
The other calendar mistake is missing the window. For 2027 coverage, HealthCare.gov open enrollment runs from November 1, 2026 through January 15, 2027. Enroll by December 15 for coverage starting January 1; enroll between December 16 and January 15 and coverage starts February 1. State-run exchanges set their own deadlines, some earlier (Idaho closes December 15) and some later (California, New York, New Jersey and DC run to January 31). Check the official dates and deadlines page for your state.
Also note that the year-round special enrollment period for people under 150 percent of poverty was suspended on HealthCare.gov in August 2025. Miss open enrollment now and you need a qualifying life event to get in mid-year.
Mistakes 8 and 9: The COBRA trap and the short-term trap
Dropping COBRA and expecting a special enrollment period
After a layoff, many people elect COBRA to keep their employer plan, then discover it costs the full premium plus a 2 percent fee. When they try to switch to a cheaper marketplace plan a few months later, they hit a wall. Voluntarily dropping COBRA, or simply not paying, does not qualify you for a special enrollment period. You can move to the marketplace during open enrollment, when your COBRA runs out, or if your former employer stops subsidizing it, but not because you changed your mind. HealthCare.gov’s COBRA page spells out the rules. Compare COBRA against a subsidized marketplace plan during the 60-day window right after you lose coverage, before you elect anything. We break down that decision in our guide to health insurance after losing a job.
Buying a short-term plan and thinking it is real insurance
Short-term limited-duration insurance is cheap because it is not health insurance in the ACA sense. Insurers can deny you or price you based on your health, exclude pre-existing conditions, cap benefits and skip essential health benefits like maternity and mental health care. Under the federal rule now on the books, plans are limited to an initial term under 3 months and 4 months total including renewals, although federal agencies said in August 2025 they would not prioritize enforcing that limit, and roughly a dozen states ban the products outright. Premium tax credits cannot be used on them, and losing one does not trigger a marketplace special enrollment period. A bridge for a few weeks is one thing; using one as your family’s coverage for the year is a serious gamble. Read the details in our short-term health insurance guide.
Mistake 10: Not filing Form 8962
If you received any advance premium tax credit during the year, you must file a federal tax return and attach Form 8962 to reconcile it, even if you would not otherwise need to file. Your marketplace sends Form 1095-A by mid-February (it is available online from mid-January) with the numbers you need.
People skip this step because their income was low or they assumed the marketplace handled it. According to HealthCare.gov, failing to reconcile can cost you advance credits in future years, which means paying full price for coverage until you catch up. Our article on health insurance and taxes shows exactly how the 1095-A and 8962 fit together.
Bottom line
Nearly every mistake above comes from treating health insurance as a one-number purchase. The plan that costs the least is the one whose total yearly cost is lowest for the care you will actually use, whose network includes your doctors, whose formulary includes your drugs, and whose subsidy you estimated honestly enough that the IRS will not want it back. In 2026 the margin for error is smaller than it has been in years: deductibles are up, the subsidy cliff is back, repayment caps are gone, and several carriers are leaving.
Block out an hour during open enrollment, run the total-cost estimate, check the directory and the drug list, and pick your plan on purpose. When you are ready to compare carriers, our rankings of the best health insurance companies of 2026 are the place to start.