November 1st is the first day of open enrollment for 2027 health insurance. If you’re under 65 and paying for health insurance before Medicare, two things are different this time. Premiums are going up for the second year in a row, and the cost of guessing your income wrong no longer has a ceiling.

A lot of people will find that out when they file their taxes this spring. Here’s health insurance explained in plain terms: how both changes work, and exactly what to check before December 15th.

The BasicsHow the Premium Tax Credit Works

If you buy your own coverage before 65, it usually comes through the Affordable Care Act Marketplace. In many states that’s HealthCare.gov. Other states run their own Marketplace, with their own deadlines.

The help with premiums is called the premium tax credit. It starts with the benchmark plan, which is the second-lowest-cost Silver plan where you live, priced for your age. Silver is the middle metal level. Bronze costs less each month and more when you use care, and Gold is the reverse.

The law sets how much of your income you’re expected to put toward that benchmark. For 2027, the most anyone in the subsidy range pays is 10.22% of household income. Your credit is the gap between the two. If the benchmark costs $1,000 a month and your share is $400, your credit is $600.

The credit is paid every month based on the income you estimate when you apply. Then it’s settled on your tax return using your real income. Keep that in mind, because it’s where the second change comes in.

The TimelineWhat Changed on January 1, 2026

From 2021 through 2025, the credit was expanded. Nobody paid more than 8.5% of their income for the benchmark plan, and higher earners could still qualify. That expansion expired on December 31, 2025.

On January 1, 2026, the original rules came back. The most important one is the cliff. Help no longer tapers off as income rises. It stops completely once household income goes over 400% of the federal poverty level.

Starting with the 2026 tax year, the caps on how much excess credit you repay at tax time were also removed. And premiums rose a median of 20% for 2026. So the people shopping this fall are dealing with a second year of change on top of the first.

The Number to KnowThe 2027 Income Line

For 2027 coverage, the 400% line is $63,840 for a single person and $86,560 for a married couple. Those figures come from the 2026 federal poverty guidelines, $15,960 for one person and $21,640 for two, multiplied by four.

The income that counts is your household income for all of 2027. That includes IRA and 401(k) withdrawals, Roth conversions and capital gains. It also includes your full Social Security benefit, even the part that isn’t taxed. If you claim Social Security early while you’re on a Marketplace plan, every dollar of that benefit counts toward the line.

Here’s how fast a couple can get there. Picture a $40,000 pension and $30,000 in IRA withdrawals. That’s $70,000, comfortably under the line. Then one spouse claims Social Security at 62 and adds $20,000. Now they’re at $90,000. That’s over $86,560, and they lose the credit for the entire year.

The Cliff$63,840 vs. $63,841

Premiums are priced by age. KFF’s national average benchmark for 2026 is $625 a month for a 40-year-old. Run that through the federal age curve and the same plan costs a 60-year-old $1,327 a month.

Take a single 60-year-old with income of exactly $63,840. She’s expected to pay 10.22% of that, which is $543.70 a month. Her credit covers the rest: $783 a month, or $9,402 for the year.

Now give her one more dollar. At $63,841, her credit is zero, and she pays the full $15,927 for the year.

One dollar of income, and about $9,400 in help disappears. That’s what people mean when they call it a cliff.

That’s an illustration built on national averages. Her real numbers depend on her county and the 2027 prices that post on November 1st. But the cliff works the same way everywhere.

The PriceProposed 2027 Increase

KFF reviewed filings from 276 insurers in all 50 states and DC and found a median proposed increase of 15% for 2027. Fifty-one of those insurers asked for more than 25%.

These are proposed rates, and state regulators review them. But last year, the median proposed increase was 18% and the final number came in at 20%.

And these increases stack. A $1,000 premium in 2025 became $1,200 after a 20% increase in 2026. Another 15% takes it to $1,380 in 2027.

Insurers point to rising medical costs first. They also point to people dropping coverage after the enhanced credits ended. The people who drop tend to be healthier, which leaves a sicker group behind, and premiums are priced for that group.

If you’re under the line and buy the benchmark plan, your credit generally rises with the price, which softens the increase. If you’re over the line, the full increase is yours.

Important NoticeNo Repayment Cap Starting in 2026

This is the change most people won’t feel until spring.

Say a single person estimates her income at 250% of the poverty level, and a part-time job pushes her to 290%. She received $4,000 more in credit than she was entitled to.

On a 2025 return, the repayment cap for her income range was $975. She’d repay $975, and the rest would be forgiven. On a 2026 return, there’s no cap. She repays the full $4,000. That’s $3,025 more for the same mistake.

The fix is to report income changes to the Marketplace when they happen, not at tax time. Your credit adjusts for the remaining months, and the gap shrinks.

Next StepsWhat to Check Before December 15

December 15th is the deadline for coverage starting January 1st on HealthCare.gov. State-run Marketplaces set their own dates. Before then, check three things.

First, update your income estimate for 2027. Don’t let an old number carry forward, and include any Social Security or Roth conversion you’re planning.

Second, look up the new benchmark in your area. If your plan isn’t the benchmark anymore, your cost can change even if nothing about your plan did.

Third, check that your doctors and prescriptions are still covered. Networks and drug lists can change from one year to the next, even when the plan name stays the same.

For 2027, the help is still there for people under the line, but the line is sharp and the cost of a wrong estimate is no longer capped. How these rules apply to you depends on your income and where you live, and benefits vary by individual situation, so run your own numbers before you renew.

Not connected with or endorsed by the United States government or the federal Medicare program.

We do not offer every plan available in your area. Any information we provide is limited to those plans we do offer in your area. Please contact Medicare.gov, 1-800-MEDICARE, or your local State Health Insurance Program to get information on all of your options.

Sources: KFF, How Much and Why ACA Marketplace Premiums Are Going Up in 2027. KFF, Marketplace Average Benchmark Premiums. IRS, Rev. Proc. 2026-26 (2027 applicable percentages). IRS, premium tax credit repayment changes. HHS, 2026 Poverty Guidelines. CMS, federal default age curve. CBPP, 2025 repayment caps. HealthCare.gov, dates and deadlines.