Medicare’s two-year income lookback means Roth conversions carried out at 63 or later immediately raise your Part B premiums when you enroll at 65.
A $200,000 conversion at 63 that pushes MAGI to $250,000 can set off roughly $3,895 in annual Part B surcharges, doubling for married {couples}.
Ages 61 to 62 offer the cleanest conversion runway for a easy purpose. Income is low before Social Security and RMDs start, and Medicare can’t see those {dollars}.
Two retirees, same $1 million, same 4% rule, buy one completed with $1.4 million, the other hit $0 in 12 years. Our free reader information explains the flaw that separated them, and the income-first technique constructed to keep away from it.
A 61-year-old with $1.4 million in a conventional 401(okay) posts the same query on retirement boards every week: convert now, wait, or unfold the tax hit across a full decade? The intuition is to stretch conversions over as many years as potential, preserving each yr’s income inside a low bracket. That intuition collides with a Medicare rule most conversion calculators ignore, and the collision begins at age 62.
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Medicare Part B makes use of a two-year income lookback. Enroll at 65, and the Social Security Administration reaches back to your tax return from age 63 to set your Income-Related Monthly Adjustment Amount (IRMAA). The last tax yr you can convert without any risk of touching Medicare pricing is the yr you flip 62. Every greenback transformed from age 63 onward is a greenback the Medicare system will see.
The Two-Year Lookback Rewrites Your Conversion Timeline
The normal Medicare Part B premium in 2026 is $202.90 per month, and roughly 92% of enrollees pay precisely that. The other 8% pay surcharges that scale exhausting. At the prime tier of $500,000 or more, the whole Part B premium runs $689.90 a month, Part D surcharges stack on prime.
The 4% Rule is Broken, Built On A World That No Longer Exists
Every retiree knows about the 4% rule, but it frames retirement as a sluggish liquidation and still causes retirees with seven-figure accounts to agonize over a dinner out.
There’s a completely different means to run the math that makes more sense at present. Build an income flooring — dividends, curiosity, and Social Security that cowl your important payments every month — and you never have to promote shares into a down market just to pay them.
Run the math on a $200,000 conversion carried out at age 63 that pushes a single retiree’s MAGI to $250,000. Two years later at Medicare enrollment, that exhibits up as roughly $528 per month in Part B, about $3,895 in annual Part B surcharges alone, plus several hundred more in Part D. For a married couple both enrolling at 65, double it. The same $200,000 conversion executed at 61 or 62 is invisible to Medicare because the MAGI precedes the lookback window solely.
What This Means for Someone Sitting on $1 Million to $2 Million
The 22% federal bracket in 2026 runs to $50,400 for singles and $100,800 for joint filers, with the 24% bracket stretching to $105,700 single and $211,400 joint. A married couple with modest other income can pull $150,000 to $200,000 into a Roth conversion at 61 and keep inside 24%, effectively below the joint IRMAA threshold of $218,000. Doing the same conversion at 63 prices the same federal tax but provides Medicare surcharges that persist for a full yr at 65.
The window is also helpful because pre-Medicare income tends to be decrease. Many readers in this bracket have retired or dropped to part-time by 60, but Social Security hasn’t began and Required Minimum Distributions are still a decade away. That is the cleanest conversion runway most retirees will ever get.
The Contribution Side Also Shifts at 60
If you’re still working, 2026 opens a separate window. The worker contribution restrict is $24,500, with a normal catch-up of $8,000 for ages 50 to 59. Ages 60 to 63 get the SECURE 2.0 tremendous catch-up of $11,250, bringing the whole to $35,750. And beginning this yr, anyone who earned more than $150,000 in 2025 must route all catch-up contributions into a Roth 401(okay), that means the whole tremendous catch-up now grows tax-free rather than tax-deferred. That is a $11,250 Roth funnel that vanishes at age 64.
Three Actions Before You Turn 63
Pull your projected MAGI for the tax yr you flip 63. If any deliberate Roth conversion pushes joint income above $218,000 or single income above $109,000, shift that conversion into your age-61 or age-62 tax yr instead.
If you’re 60 to 63 and still working with W-2 wages above $150,000, confirm your plan affords a Roth 401(okay). Without one, you lose the whole $11,250 tremendous catch-up.
Model conversions against the 24% bracket ceiling of $211,400 joint, not against IRMAA. The bracket nearly always binds first at these balances, and staying under it retains the conversion mathematically clean.
The 2.8% Social Security COLA for 2026 and the 3.75% Fed Funds price both matter less to this determination than the calendar does. The conversion window has an expiration date, and it’s your 63rd birthday.
Before Your Next Withdrawal, Run One Number ( It’s Not The 4% Rule Everyone Knows)
Take your important month-to-month bills and subtract your assured income — Social Security, plus any pension. What’s left is your income hole, and how you close it determines whether retirement runs on share gross sales or on a paycheck your portfolio writes you every month. Our free reader information, The 4% Rule Is Broken, exhibits precisely how to close that hole with portfolio income: a labored instance (one retiree needed about $480,000 in income-producing belongings to cowl his necessities for good), an eight-point conversion guidelines, and the 20-year numbers evaluating dividends to withdrawals. It’s free and takes about quarter-hour to learn. Get the information here before you take your next withdrawal.
