The $2,800 Medicare letter nobody warns you about

Every year around Thanksgiving, a batch of letters goes out from the Social Security Administration that ruins a lot of dinners. It’s a plain envelope. Inside, it says your Medicare Part B and Part D premiums are going up because of your income, and it names a number that can run from a few hundred dollars a year to several thousand.

Most people have never heard of it until it lands in the mailbox. I hadn’t either, until a neighbor showed me his. So let’s walk through it the way I wish someone had walked me through it.

Quick housekeeping first: I’m not a financial advisor and this isn’t advice. I’m a guy at a kitchen table who reads the fine print so you don’t have to.

What IRMAA actually is

The letter is about something called IRMAA. It stands for Income-Related Monthly Adjustment Amount, which is government language for “you earned more than the line, so you pay more for Medicare.”

Here’s how it works. Everyone on Medicare pays the standard Part B premium. If your income is above a certain threshold, Social Security adds a surcharge on top of that premium. There’s a separate surcharge for Part D drug coverage, too, and it applies even if you get your drug coverage through a Medicare Advantage plan.

The surcharge comes in tiers. The higher your income, the higher the tier. At the top, people pay several times the standard Part B premium.

The exact thresholds and amounts change every January, so I’m not going to print numbers that will be wrong by the time you read this. The first line currently sits a little above $100,000 for a single filer and about double that for a couple filing jointly. You can find the current table on medicare.gov by searching “Part B costs.”

The headline figure in my title is a round number for what the Part B and Part D surcharges together can cost one person in the middle brackets over a year. For a couple, double it. That’s real money coming out of a Social Security check.

The two-year lookback is the part that bites

Here’s the catch that surprises almost everyone. Social Security doesn’t look at what you earn this year. It looks at the tax return you filed two years ago, because that’s the most recent one the IRS has fully processed and shared with them.

So the letter you get in late 2026 about your 2027 premiums is based on your 2025 tax return. What you earn in 2027 doesn’t matter yet. It’ll show up in 2029.

And the income they use isn’t quite your taxable income. It’s what they call modified adjusted gross income: your adjusted gross income plus any tax-exempt interest, like municipal bond interest. So some income you thought was “tax-free” still counts here.

One more thing. The thresholds are cliffs, not ramps. Go one dollar over a line and you pay the full surcharge for that tier, for the whole year. There’s no partial credit.

How one good year can cost you

This is why the letter blindsides retirees who think of themselves as living on a modest income. IRMAA doesn’t care whether your income was normal or a one-time spike. It just reads the number on the return.

The usual suspects:

• Selling a house. If the gain is above the home-sale exclusion, the extra shows up as income that year.
• A Roth conversion. Moving money from a traditional IRA to a Roth is a taxable event, and a big conversion can push you over a line.
• Required minimum distributions. Once RMDs kick in, that withdrawal is income whether you needed the money or not.
• Cashing out an investment, a pension lump sum, or an inherited IRA. Each one lands on the return as income in the year it happens.
• A final big year of work before you retired, with a bonus or severance on top.

Any one of these can land you in a tier two years later, long after the money is spent and you’ve forgotten about it. That’s the “nobody warns you” part. The real-estate agent, the broker, and the HR office all did their jobs. None of them had a reason to mention Medicare.

The appeal: form SSA-44

Here’s the good news. If your income dropped because of a life-changing event, you can ask Social Security to use a more recent year instead. The form is called SSA-44, “Medicare Income-Related Monthly Adjustment Amount – Life-Changing Event.” You can download it from ssa.gov.

Social Security recognizes a specific list of events: marriage, divorce or annulment, death of a spouse, stopping work, reducing your work hours, losing income-producing property through something outside your control, losing a pension, or receiving an employer settlement payment.

Retiring is the big one. If you were working two years ago and you’re not now, you almost certainly qualify. You fill out the form, estimate your current-year income, attach proof like a retirement letter, and they recalculate.

Now the part people don’t like to hear. A house sale, a Roth conversion, and an RMD are not on the list. Those are considered your choices, not life events. If that’s what put you over, the SSA-44 won’t help, and you’re generally going to pay the surcharge for that one year.

You can still file a regular appeal (a “request for reconsideration”) if you think Social Security used the wrong tax year or the wrong numbers. That happens more than you’d think, especially if you filed an amended return.

What to do the year before

Since the lookback is two years, the time to think about IRMAA is before the income happens, not after the letter comes. A few things worth asking your tax preparer about:

Know where the lines are. Pull up the current IRMAA table and write the first threshold on a sticky note. If you’re anywhere near it, every decision below matters.

Spread big events out. If you’re planning a Roth conversion, ask whether splitting it across two or three tax years keeps you under a line each year. Same with selling something that carries a big gain.

Ask about qualified charitable distributions. After age 70 and a half, money sent directly from an IRA to a charity can count toward your RMD without showing up in your adjusted gross income. If you already give to your church or a cause, this is worth a conversation.

Watch the year you sell the house. If you have flexibility on timing, closing in January instead of December moves the gain to a different tax year. Sometimes that’s the difference.

Remember the cliff. If you’re going to be over a line anyway, being over by a lot doesn’t cost more than being over by a little. If you’re going to be under, stay under.

If the letter already came

Don’t panic, and don’t ignore it. Read it carefully. It’ll tell you which tax year they used and what income they counted.

If that year doesn’t reflect your life now because you retired, lost a spouse, or something else on the list, file the SSA-44. You can do it at your local Social Security office or by mail. Bring proof.

If the year was simply a one-time spike, set the money aside and mark the calendar. The surcharge is recalculated every year. When the next return shows normal income, it goes away on its own. Think of it as a one-year toll, not a life sentence.

And next time you’re about to do something big with money, add one question to the list: what will this do to my Medicare premium two years from now? Most people never ask it. Now you will.

Read what Medicare won’t tell you in Fixity Health Confidential.