If you retire before 65, there's a stretch of years most people don't think much about until they're standing in the middle of it: the gap between leaving your job and becoming eligible for Medicare. For someone who retires at 55, that's a full decade. For someone who retires at 62, it's three years. Either way, this window quietly shapes your healthcare costs — not just during those years, but sometimes for the rest of your life.

Here's why it deserves more attention than it usually gets.

The insurance problem nobody warns you about

Once you leave a job, you typically lose employer health coverage. Until Medicare kicks in at 65, most early retirees buy health insurance through the ACA marketplace (the same place people without employer coverage have shopped since the Affordable Care Act). Marketplace plans can be expensive on their own — but most people qualify for a subsidy that brings the cost down significantly, based on their income.

That subsidy is the whole story. And it comes with a catch most people don't discover until it costs them something.

The cliff, not the slope

Most tax benefits phase out gradually — earn a little more, get a little less. The ACA subsidy doesn't always work that way. Depending on where you live and the specific plan, going even slightly over a certain income threshold in a single year can mean losing your entire subsidy for that year, not just a portion of it. Not a gentle slope — a cliff.

That means a decision that seems small in the moment — converting a bit more of a retirement account to a Roth, selling an investment with a large gain, taking a slightly bigger withdrawal than usual — can, in the wrong year, cost you thousands of dollars in lost subsidy. Not because the decision itself was bad, but because of when it happened.

Why this window is also your best opportunity

Here's the twist: this same stretch of years is often the single best opportunity you'll get to do smart, low-tax retirement planning — specifically, converting money from a traditional retirement account to a Roth account at a low tax rate (a topic we covered in an earlier post in this series).

Why? Because during these years, you likely have no paycheck, Social Security probably hasn't started yet, and Medicare's income lookback hasn't started counting against you yet either. Your taxable income is about as low as it will ever be in retirement. That's exactly when converting money to a Roth costs the least in tax.

So this decade does double duty: it's the window where a wrong move costs you the most (a lost subsidy), and it's also the window where a well-timed move saves you the most (cheap Roth conversions). Those two forces are pulling in opposite directions, and the only way to actually thread the needle is to know, in dollars, exactly where the subsidy cliff sits for your household — and how much room you have to convert before you'd cross it.

A simple way to think about it

Imagine your income during these years as water filling a glass. There's a line partway up the glass — the subsidy cliff. Below the line, you're fine, and you might even have room to do a Roth conversion or two without spilling over. Above the line, the subsidy is gone, possibly for the whole year, over what might have been a difference of a few hundred dollars in income.

The problem is, most people can't see the line. They're filling the glass with Roth conversions, investment sales, or extra withdrawals, without a clear read on how close they are to spilling over — until the tax return the following year tells them what happened, after it's too late to undo it.

What a good plan should be doing here

If you're in (or approaching) this window, a retirement plan that's actually doing its job should be able to tell you, in plain terms:

  • How much income "room" you have this year before you'd lose your health insurance subsidy
  • Whether it's using that room for a Roth conversion, and if so, why that amount
  • What the actual dollar value of the subsidy is, so "don't go over the line" isn't just an abstract warning but a concrete number worth protecting

If your current plan can't answer those three things for your specific numbers, it's not fully doing the job during the years when the stakes are highest.

The takeaway

The ten years before Medicare aren't just a bridge to get through — they're one of the most consequential stretches in your entire retirement, financially speaking. Handled well, this window can meaningfully lower your lifetime taxes. Handled carelessly, it can quietly cost you thousands in a single year, without you ever seeing it coming until the bill arrives.

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Next in this series: Should You Trust a Retirement Tool That Shows Its Work?