Which Account Goes First? The Question Every Couple With $1.4 Million Should Answer Before 65
Most couples at 63 focus on which accounts to preserve, but the real danger is the sequence of withdrawals they lock in before Medicare starts. A two-year window before 65 can either protect your premiums and tax bracket for decades…
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A couple both age 63 sitting on $1.4 million across a traditional 401(k), a Roth IRA, and a taxable brokerage account has a two-year window most retirees waste. The real question is which account to touch first. Get the sequence wrong before Medicare enrollment at 65, and you can lock in Part B surcharges that follow you for years.
The default advice, taxable first, then traditional, then Roth, is only a starting point. The couple with $1.4 million has to solve for four moving parts at once: the Social Security tax torpedo, the IRMAA two-year lookback, the RMD wave that hits at 73, and the widow’s trap that turns a joint filer into a single filer overnight.
Why 63 to 65 Is the Decision Window
Assume the balance splits roughly $1 million traditional 401(k), $250,000 Roth IRA, and $150,000 in a taxable brokerage. Neither spouse has claimed Social Security yet. Both plan to enroll in Medicare at 65.
Here is the trap. Medicare uses a two-year lookback on modified adjusted gross income to set Part B and Part D premiums. Income reported on the 2026 tax return determines 2028 IRMAA surcharges. A large 401(k) withdrawal or Roth conversion at 63 shows up in premiums the year Medicare starts.
The 2025 married-filing-jointly brackets give this couple room to work. The 12% bracket runs to $96,950 and the 22% bracket runs to $206,700. Every dollar of 401(k) they convert or withdraw at 22% now is a dollar they will not pull at a higher effective rate later, when RMDs, Social Security, and a possible surviving-spouse filing status stack together.
Sequence That Actually Cuts the Lifetime Tax Bill
Start with the taxable account for cash flow. Long-term gains at 0% or 15% cost less than ordinary-income withdrawals from the 401(k). Reserve one to two years of spending in Treasurys: the 1-year Treasury yields 4.45% and the 6-month yields 4.22%, so a short ladder covers the runway without touching retirement accounts.
Then, and this is where most couples stop, run partial Roth conversions from the 401(k) each year through age 72. If you convert $80,000 annually from age 63 to 72, you fill the 12% and lower end of the 22% bracket and shrink the traditional balance before RMDs begin. That gap between the last paycheck and the first required withdrawal may be the lowest tax rate this couple ever sees again, which is the whole point of our free Roth window guide. As Suze Orman has pointed out, money withdrawn from a Roth does not count toward Social Security taxation or Medicare Part B premium calculations. Money from the traditional 401(k) counts toward both.
Delaying Social Security to 70 amplifies the strategy. Benefits grow roughly 8% per year of delay past full retirement age, and the 2027 COLA is tracking toward 3.3%, compounding on top of that larger base. Larger Social Security means less pressure on the portfolio later, when the 401(k) balance is smaller and RMDs are manageable.
Tax Cascade in Plain Numbers
Once combined income crosses the upper threshold, 85% of Social Security becomes taxable. Add IRMAA at $103,000 single or $206,000 joint MAGI and Part B premiums step up. A couple in the 22% bracket triggering both can face an effective marginal rate near 40% on the next dollar of 401(k) withdrawal. That is the cost of doing nothing between 63 and 65.
Note that RMDs are calculated across all traditional IRAs combined, though the withdrawal can come from any one account. Shrinking the traditional balance before 73 directly shrinks the future RMD.
Three Actions Before You Turn 65
- Model a conversion ladder to the top of the 22% bracket. Using the $206,700 ceiling on the 22% MFJ bracket, calculate the largest annual conversion that keeps MAGI below the first IRMAA tier. Do it before the calendar year you turn 63, because that return sets your 65 Medicare premium.
- Build a two-year Treasury reserve for spending. With the federal funds upper target at 3.75% and the 1-year Treasury at 4.45%, short bills fund living expenses while conversions run, so you are not pulling extra taxable income from the 401(k).
- Coordinate Social Security claiming with the conversion window. Delay benefits to 70, finish conversions by 72, and let RMDs at 73 land on a smaller pre-tax base. If MAGI is on track to breach $206,000, a fee-only advisor pays for themselves in avoided IRMAA alone.
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Jake has been been working in financial media for almost 15 years. He focuses on all things personal finance for 24/7 Wall St. with high hopes to educate and entertain. Most recently, Jake spent 12 years working various roles at The Motley Fool. He started copy editing fool.com content, worked on premium and marketing campaigns, and helped launch The Ascent, a personal finance brand.
His work has been featured on platforms like MSN, Yahoo Finance, USA Today, and more. He's written about credit cards, social security, ETFs, savings accounts, and just about anything else you can imagine when thinking about money. Jake love to cook, play golf, and tell people he's never had a cavity. (It's true!)
