401(k) vs. Roth: Which Strategy Wins Depends on One Critical Factor, Expert Explains

On a recent Earn Your Leisure episode titled “Retire Rich The Ultimate Guide to IRAs, 401(k)s, & HSAs!”, a guest delivered the line every traditional 401(k) saver needs to hear: “If you have, let’s say, $1 million in retirement and you took out that whole million dollars at one time from your 401k, you would get like $600,000 net because that is fully taxable.”

If you have been maxing a pre-tax 401(k) for two decades and watching the balance climb, that sentence should reset your retirement math. The seven-figure number on your statement is partly a sizable IOU to the IRS.

The Math Is Brutal

Every dollar inside a traditional 401(k) gets taxed as ordinary income on withdrawal. Pull the entire $1 million in a single year as a single filer and you crash through every federal bracket.

Under the 2026 brackets, ordinary income above $640,600 for a single filer is taxed at the top 37% federal rate. The lower slices stack underneath: 35% over $256,225, 32% over $201,775, 24% over $105,700, 22% over $50,400, 12% over $12,400, and 10% below that. Subtract the $16,100 standard deduction and almost the entire million still gets taxed, with the bulk in the 32%, 35%, and 37% brackets.

Add a state with a 5% to 10% income tax and the guest’s $600,000 net estimate is roughly where you land. A 40% combined haircut on a one-shot withdrawal is the base case.

The Roth side mirrors this: “If you have the Roth, if you have a million dollars hypothetically and you took out all the million dollars at one time, you would get $1 million because it’s not taxable.” You paid the tax going in, so the IRS has no further claim.

The Single Factor That Decides Roth vs. Traditional

Whether your tax rate in retirement will be higher or lower than today determines which account wins.

Take a 35-year-old earning $120,000. Their top dollar is taxed at 24%. A $20,000 traditional 401(k) contribution saves roughly $4,800 in federal tax this year. Retiring at 65 with $1 million and pulling $80,000 annually puts their effective federal rate closer to 12% to 15% after the standard deduction. Traditional wins.

A 28-year-old in California earning $70,000 with top dollar in the 22% federal bracket and expecting strong income growth will likely retire in a higher bracket. Roth contributions lock in the 22% rate now and shield decades of compounding from future rate hikes. Roth wins.

The traditional 401(k) is a bet that your future self will be poorer in tax terms than your present self. For high earners at 32% who plan to live well in retirement, that bet often loses.

The Capital Gains Cliff

The same segment flagged a second tax cliff outside retirement accounts. Short-term capital gains, on positions held a year or less, are taxed as ordinary income and can run as high as 37 to 39% with state tax. Long-term gains on positions held more than a year typically sit at 15%, or 20% at the top end. The guest’s framing was blunt: “20% difference if you just hold long-term.”

Selling on day 365 versus day 366 of a $50,000 gain is a five-figure decision. In a taxable brokerage account, the calendar is part of the strategy.

State Tax and Default Strategies

State tax is the silent partner in every withdrawal. A retiree pulling $80,000 a year from a traditional 401(k) in New York hands over thousands more annually than the same retiree in Florida, which is why many retirees relocate to Florida for its lack of state income tax. The federal bill is fixed. The state bill is a choice.

For savers paralyzed by investment options, the show pointed to target date funds, named by retirement year like 2030, 2040, or 2050, which automatically rebalance from aggressive to conservative allocations as the saver approaches the target. They are not optimal for everyone, but they beat sitting in cash.

What To Do This Week

1. Log into your 401(k) and check whether your plan offers a Roth option. Many do, and most participants never toggle it on.
2. Estimate your current marginal federal bracket using the 2026 brackets, then estimate your taxable income in retirement. If retirement income looks lower, keep contributing traditional. If it looks higher or uncertain, route new contributions to Roth.
3. Run a withdrawal simulation: take your current pre-tax balance, assume a 4% annual draw, and apply your projected retirement bracket plus state tax. That number is your real retirement income.
4. For any taxable brokerage positions sitting on gains, check the purchase date before selling. Crossing the one-year-and-a-day line changes the tax rate from ordinary income to 15% or 20%.

The balance on your 401(k) statement is a gross figure. Plan around the net.