Roth vs Traditional 401(k) on $100k income? (married)
Elena & Tyler, 35 and 33, in Denver, CO
exampleMarried, no kids yet · $100k/yr household income
They're maxing their 401(k) in Denver and unsure whether Roth or traditional is quietly costing them.
Elena & Tyler are maxing their 401(k) in Denver and paying an 18% marginal rate to do it. The question isn't which account sounds better. It's whether they'll owe more tax now or in retirement, and the math has a clear answer.
The setup
Age
35
Household income
$100,000/yr
Household
Married, dual income
Liquid savings
$44,000
Retirement savings
$132,000
Investing return
7%/yr
Lean Traditional, your 18% rate drops to ~10% in retirement
18% → 10%
Rate drops 8% in retirement
Rate Now
18%
Rate Retired
10%
Best Strategy
All Trad
NW Diff
+$331k
Their marginal rate today is 18%, but the engine projects it dropping to roughly 10% in retirement, an 8-point gap that works strongly in favor of the traditional 401(k). That spread, compounded across decades, is where the $331k net worth difference comes from. Paying tax at 18% now, when you could defer and pay 10% later, is the most expensive kind of well-intentioned mistake.
Your current effective rate of ~18% (engine-computed) drops to ~10% in retirement. Traditional saves taxes now when your rate is highest. The All Trad strategy produces +$331k more at retirement.
| Scenario | Strategy | Retire NW | Lifetime Taxes | Retire SWR/mo | Coverage |
|---|---|---|---|---|---|
| All Trad | 100% Traditional | $6,576,685 ($2.7M in today's dollars) | $2.9M | $21,922 | 25 yrs |
| Current | Current mix | $6,245,634 ($2.6M in today's dollars) | $2.1M | $20,819 | 25 yrs |
| 50/50 | 50/50 Split | $6,366,636 ($2.6M in today's dollars) | $2.3M | $21,222 | 25 yrs |
| Roth 70% | Tilt Roth (70%) | $6,226,451 ($2.6M in today's dollars) | $2.0M | $20,755 | 25 yrs |
| All Roth | 100% Roth | $6,128,793 ($2.5M in today's dollars) | $1.8M | $20,429 | 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.
Your own rate gap might be wider or narrower than Elena and Tyler's, so run your numbers and find out exactly what that difference is worth to your household.
Model your own version, free
Your real answer depends on your full picture. Build it in under a minute.
Get my verdict →Frequently asked
Roth or traditional 401(k) for a married household earning $100k?
Lean Traditional, your 18% rate drops to ~10% in retirement
Rate drops 8% in retirement
18% → 10%, 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.
Related scenarios
Related guides
For educational purposes only, not financial advice.