Roth vs Traditional 401(k) on $300k income? (married)
Nina & Leah, 35 and 37, in Boston, MA
exampleMarried, no kids yet · $300k/yr household income
They're maxing their 401(k) in Boston and unsure whether Roth or traditional is quietly costing them.
Nina & Leah are maxing their 401(k) in Boston on $300k and paying 23% on every dollar they put in Roth. The math says that's the wrong call, and the gap is bigger than it looks.
The setup
Age
35
Household income
$300,000/yr
Household
Married, dual income
Liquid savings
$132,000
Retirement savings
$396,000
Investing return
7%/yr
Lean Traditional, your 23% rate drops to ~17% in retirement
23% → 17%
Rate drops 6% in retirement
Rate Now
23%
Rate Retired
17%
Best Strategy
Current
NW Diff
$0
The engine projects their effective tax rate drops from 23% now to roughly 17% in retirement, a 6-percentage-point spread. That means every dollar they contribute Roth today gets taxed 6 points harder than it needs to be. Shifting to traditional captures that spread and invests the tax savings now, when compounding has 30 years to work.
Your current effective rate of ~23% (engine-computed) drops to ~17% in retirement. Traditional saves taxes now when your rate is highest. The Current strategy produces $0 more at retirement.
| Scenario | Strategy | Retire NW | Lifetime Taxes | Retire SWR/mo | Coverage |
|---|---|---|---|---|---|
| All Trad | 100% Traditional | $25,361,395 ($10M in today's dollars) | $11M | $84,538 | 25 yrs |
| Current | Current mix | $25,110,533 ($10M in today's dollars) | $10M | $83,702 | 25 yrs |
| 50/50 | 50/50 Split | $24,779,429 ($10M in today's dollars) | $9.5M | $82,598 | 25 yrs |
| Roth 70% | Tilt Roth (70%) | $24,480,089 ($10M in today's dollars) | $8.9M | $81,600 | 25 yrs |
| All Roth | 100% Roth | $24,190,136 ($10.0M in today's dollars) | $8.3M | $80,634 | 25 yrs |
Tax laws change. Roth conversions, RMDs, and state tax changes can shift the calculus. This analysis uses current rates as a starting point.
Plug your own income, savings, and retirement spending into Rightmont to see exactly where your rate lands, because the difference between 23% and 17% isn't small when it's multiplied across decades of contributions.
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Get my verdict →Frequently asked
Roth or traditional 401(k) for a married household earning $300k?
Lean Traditional, your 23% rate drops to ~17% in retirement
Rate drops 6% in retirement
23% → 17%, modeled with Rightmont's projection engine for this exact scenario.
How was this calculated?
Rightmont runs your numbers through a year-by-year projection engine (taxes, compounding, Social Security, and your real cashflow) to model the outcome. Model your own version free in under a minute.
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For educational purposes only, not financial advice.