What changes when you go from ACA to Medicare at 65?

By James·22 October 2026

You are 64, your health plan comes from the marketplace, and Medicare starts the month you turn 65. The marketplace set your price by your income and your state. Medicare charges one Part B premium everywhere: $202.90 a month in 2026, unless your income is high. Above $62,600 of income for one person, the move saves thousands of dollars a year. Below about $36,500, Medicare costs more than the marketplace plan did.

Medicare costs the same in every state, and the marketplace did not

On the marketplace, the premium tax credit sets what you pay for the benchmark plan. That is the second-lowest-cost silver plan where you live. Between 100% and 400% of the poverty line, you pay a fixed share of your income for it. In 2026 that share runs from 2.10% to 9.96%.

Above 400%, the credit stops and you pay full price. For 2026 coverage the line is $62,600 for one person. For a couple it is $84,600.

Medicare does not look at your state. Part B is $202.90 a month in 2026 for anyone with income up to $109,000. For a couple filing jointly the limit is $218,000. A stand-alone drug plan averages $34.50 a month, on CMS's projection for 2026. Together that is $237.40 a month, or $2,848.80 a year for each person.

The table runs both through this site's health engine, the one behind the state study. It prices one person aged 64 on the benchmark plan, in a state where only the federal credit applies.

Below about $36,500 of income, the marketplace plan cost less than Medicare will. At $25,000, the benchmark plan cost $1,165 a year after the credit. That is $97 a month. Medicare costs $1,684 a year more.

Above that income, Medicare is cheaper, and the gap widens as income rises. For a couple both 64, the crossing point is about $60,100.

Marketplace: KFF's 2026 state average premium for the benchmark plan, scaled from 40 to 64 by the federal age curve. The credit follows IRS Rev. Proc. 2025-25. Medicare: the CMS 2026 Part B premium and CMS's projected average stand-alone drug plan. Premiums only. The methodology describes the engine. Computed October 22, 2026.

These are premiums alone. Original Medicare has no yearly cap on what you pay. Medigap and Medicare Advantage are the two common ways to limit it, and both come up below.

Above $62,600, the drop at 65 is largest, and your state sets it

Past the 400% line, the credit is zero. A 64-year-old pays the plan's full price, and that price depends on the state. The benchmark plan for one person aged 64 averages $817 a month in New York. In Wyoming it averages $2,559.

So a single 64-year-old in Wyoming above the line pays $30,704 a year for the benchmark plan. At 65, Part B and an average drug plan cost $2,848.80. The difference is $27,855 a year. A couple both 64 there pays $61,408, against $5,697.60 for two people on Medicare.

New York and Vermont charge every adult the same rate, whatever the age. That is why New York comes out cheapest at 64. A few states add their own premium help on top of the federal credit, and the table shows prices before it. Counties also differ, by about 1.4 times between a state's cheapest and dearest.

Medicare charges more at high incomes, but nowhere near the marketplace's full price. Above $109,000 for one person, Part B and Part D each carry a surcharge called IRMAA. At $120,000, one person pays $3,997.20 a year for Part B and an average drug plan. That is $333.10 a month.

Medicare reads that income from your tax return two years back. For 2026 premiums, Social Security uses the 2024 return. A year of high income at 63 can raise your premiums at 65. If your income fell because you stopped working, Form SSA-44 asks Social Security to use the lower year instead.

Full price: KFF's 2026 state average benchmark premium (CMS data), scaled to 64 by each state's age curve. Saved at 65: that price less $2,848.80 for Part B and an average drug plan, below the IRMAA line. Under each state: CMS's 2026 average Medicare Advantage premium a month, before Part B, which is still owed. Computed by this site's engine; see the methodology.

The sign-up dates that cost money for life

This is the step where the move costs money, and the cost can last for life. Two things have to happen on time. You sign up for Medicare inside its window. And you end the marketplace plan yourself, so the credit stops when Medicare starts.

Medicare's seven-month window

Your Initial Enrollment Period lasts 7 months. It opens 3 months before the month you turn 65 and closes 3 months after it. Premium-free Part A starts the month you turn 65. Part B starts that month too if you sign up before it.

Sign up in your birthday month or later, and Part B starts the month after you sign up. A birthday on the 1st moves everything one month earlier. If you already get Social Security checks, you are enrolled in Parts A and B automatically. Otherwise, you sign up with Social Security.

Your marketplace plan does not end on its own

HealthCare.gov says it in one line: Marketplace coverage doesn't end automatically when Medicare starts. You end it on your marketplace application. You can report your Medicare start date up to 3 months ahead. The plan then ends the day before Medicare starts.

Medicare from June 1 means marketplace coverage through May 31. Anyone else on the application keeps their plan. After the update, confirm the plan for each person staying on it.

The tax credit you would repay

The credit stops once you are eligible for premium-free Part A. HealthCare.gov is blunt about it: You'll have to pay full price for your Marketplace plan. Leave the plan running with the credit still paid, and you repay that credit on your federal return.

From 2026 there is no cap on that repayment. The tax code adds the whole excess to your tax for the year (26 U.S.C. 36B(f)(2)). At $40,000 of income in Oklahoma, the credit on a 64-year-old's plan is about $1,131 a month. Each month the plan runs past Medicare's start adds about that much to the bill.

The marketplace does not protect you from the Part B penalty

Delaying Part B without a penalty takes job-based coverage from your current work or your spouse's. That coverage gives a Special Enrollment Period later. A marketplace plan gives none. Medicare.gov adds that COBRA does not count either.

Miss the 7 months, and Part B waits for the General Enrollment Period, January 1 to March 31. Coverage starts the month after you sign up. The premium then rises 10% for each full 12 months you could have had Part B. That surcharge lasts as long as you have Part B.

It does not wear off with time.

Medicare.gov works one example. Two years late adds 20%. The 2026 premium becomes $243.50 a month instead of $202.90. At 10% a year, each year late costs $20.29 a month at 2026 prices, for life.

The Part D penalty adds 1% of $38.99 for each month without drug coverage as good as Part D. Marketplace drug coverage does not have to meet that test. Your plan must tell you in writing each year whether it does. A short gap costs little: Medicare.gov's 14-month example adds $5.50 a month.

If you would have to pay for Part A

Premium-free Part A takes 40 quarters of Medicare-covered work. With 30 to 39 quarters, Part A costs $311 a month in 2026. With fewer, it costs $565. In that case HealthCare.gov lets you choose the marketplace instead, with the credit. The late penalties for Part B and Part D still apply if you join Medicare later.

Medigap gives you one six-month window with no health questions

Original Medicare pays 80% of most Part B costs after a $283 deductible in 2026. Your 20% share has no yearly limit. A marketplace plan had one: $10,600 for one person in 2026. Two products fill that gap.

Medigap pays some or all of the 20%, beside Original Medicare. A Medicare Advantage plan replaces Original Medicare and sets its own yearly limit.

The time to buy Medigap is the 6 months that start when your Part B starts, at 65 or older. In that window an insurer must sell you any policy it offers, whatever your health. After it, an insurer may ask health questions and refuse you.

The window happens once.

Choose Medicare Advantage at 65 and change your mind within the first year, and you can still buy a Medigap policy. Medicare calls this a trial right.

Medicare Advantage premiums are low on average. The 2026 state averages run from $0 a month in Vermont to $73.51 in North Dakota. In 38 states every resident can pick a plan with a $0 premium. Alaska has no plans. Part B is owed on top of any plan premium.

Medigap prices are not in any official national file. Medicare's plan finder lists them by ZIP code, and the same lettered plan costs different amounts at different companies. Medicare's guide puts it this way: Price is the only difference between policies with the same letter sold by different companies. Get quotes from more than one company for the plan letter you want.

Your state takes some help away at 65 and offers other help

Some states add their own premium help to the marketplace credit. California's is the California Premium Subsidy, open only to people enrolled in a Covered California plan. That help ends with the marketplace plan.

Medicaid expansion ends too. Federal law covers that group only while they are under 65 years of age (42 U.S.C. 1396a(a)(10)(A)(i)(VIII)). From 65, Medicaid runs on the state's other rules. The state Medicaid office decides them.

The bigger change is what gets counted. The marketplace credit looked at income alone.

At 65, your savings count too.

Medicare Savings Programs are run by each state's Medicaid office. They pay the Part B premium. The lowest-income tier also covers deductibles and copays. For one person in 2026, the federal income limits run from $1,350 a month to $1,816.

Resources must be under $9,950, or $14,910 for a couple. Medicare.gov counts Money in a checking, savings, or retirement account as a resource. So a 64-year-old with $25,000 of income and $400,000 in an IRA got a large marketplace credit. At 65, that IRA alone is over the federal resource limit.

States may go higher. Medicare.gov says you may still qualify for these programs in your state even if your income or resources are higher than the federal limits listed. Apply through the state even when the federal limits look out of reach.

Extra Help, the federal program for drug costs, has its own 2026 limits. For one person they are $23,940 of income and $18,090 of resources. For a couple they are $32,460 and $36,100. Anyone in a Medicare Savings Program gets Extra Help automatically.

Some states run their own drug programs on top of Part D. New York's EPIC covers residents 65 and older with income up to $75,000 single or $100,000 married. It pays after the Part D plan does.

Medigap rules differ by state as well. Massachusetts, Minnesota and Wisconsin standardize their policies their own way. Some states add Medigap open enrollment periods beyond the federal one. The state insurance department lists them.

Every state has a State Health Insurance Assistance Program, or SHIP, with free counseling on all of this. SHIPs are not tied to any insurance company. The number for yours is at shiphelp.org.

If one of you is still under 65

A spouse under 65 keeps the marketplace plan. End coverage only for the person starting Medicare, then confirm the other person's plan. The younger spouse's credit is still figured on the whole household's income, with a family size of two (26 U.S.C. 36B(d)).

Take a couple with $80,000 of income, one 65 and one 63. The 63-year-old's benchmark plan costs $7,968 a year after the credit. That is $664 a month. Above $84,600, the younger spouse pays full price, from $9,804 to $30,213 a year by state.

The year you turn 65 has one more catch. The credit for your marketplace months is figured on the whole year's household income (26 U.S.C. 36B(b)(2)). Income you take after Medicare starts still counts toward it.

What these figures leave out

I priced premiums only. Deductibles, copays and the 20% share are not in the tables, and that is where Medigap and Medicare Advantage differ most. The marketplace prices are state averages, not your county's.

The 2027 figures are not out yet. Applications for 2027 marketplace coverage open on November 1, 2026. CMS published 2026's Part B premium on November 14, 2025, and this page moves to 2027's when CMS publishes it. For 2027 coverage, the 400% line rises to $63,840 for one person and $86,560 for two.

What the tables give you is the premium change at 65 at each income, with every input stated. The study of how long $500,000 lasts in every state runs the same engine. Its "Your numbers" form prices your own state and income, year by year.

Five dates to write down before you turn 65

Take someone turning 65 on June 15, 2027. These are the dates that matter, worked out from the rules above.

• March 1, 2027. Medicare's 7-month window opens. Sign up for Part B, and a drug plan or a Medicare Advantage plan, before June 1, 2027 so all of it starts that day. Report the Medicare start date on your marketplace application from this day too.
• May 31, 2027. The marketplace plan's last day, if you reported the start date.
• June 1, 2027. Part A, Part B and the drug plan start, and the 6-month Medigap window opens.
• September 30, 2027. The 7-month window closes. After it, Part B waits for the General Enrollment Period, from January 1, and each full 12 months without it adds the penalty.
• November 30, 2027. The Medigap window closes. After it, an insurer may ask health questions and turn you down.

Three questions are worth settling before the first of those dates.

Is a Roth conversion planned for 63 or 64? At 64 it raises the income the marketplace counts and can push you over the 400% line. At 63 it counts toward the income that sets your Medicare premiums at 65. The Roth conversion calculator shows the tax on each amount.

Does your marketplace plan's drug coverage count as creditable? The yearly notice says so, and it decides whether a late drug plan carries a penalty.

Which tax return will Medicare read? For premiums in 2027, it is the 2025 return, or the one before if that is the latest the IRS has passed on. The guide to what retirement actually costs in each state prices the rest of the budget at 65.

Printed from https://savingslast.com/aca-to-medicare-at-65/ on . The figures reflect the inputs shown and the rules as published on that date.