Roth and traditional employee deferrals share one 2026 cap: $24,500. The live tool compares the same gross dollars, not two different paycheck costs.
$10,000 deferred, 20 years, 7% return:
- 22% now and 12% later: traditional after tax $34,053.22, Roth $30,183.54. Traditional wins. Tax saved this year $2,200.
- 22% now and 22% later: both $30,183.54. Tie.
- $24,500 at 22% / 22%: both $73,949.67. Tie. Tax saved now $5,390.
- $24,500 at 22% now / 32% later: traditional $64,468.94, Roth $73,949.67. Roth wins.
Run the Roth vs traditional 401(k) calculator →
Match first if the plan pays one: IRA vs 401(k). Hub: United States calculators.
Traditional $10,000 costs less on this year’s stub (FIT falls). Roth $10,000 is after-tax. The engine still grows $10,000 in both columns so the rate bet is isolated. Employer match is usually pre-tax even if you pick Roth. Estimate, not investment advice.
Direct answer: 22% → 12% favors traditional
- Growth factor = 1.07^20
- Traditional future value after tax = $10,000 × growth × (1 − 0.12) = $34,053.22
- Roth future value = $10,000 × (1 − 0.22) × growth = $30,183.54
- Gap: $3,869.68 in traditional’s favor
If the two rates are equal, the (1 − rate) term cancels and the columns match.
Traditional FV after tax = C × (1 + r)^n × (1 − retirement rate)
Roth FV = C × (1 − current rate) × (1 + r)^n
Checks you can re-run
| Deferral | Now | Later | Traditional after tax | Roth | Winner |
|---|---|---|---|---|---|
| $10,000 | 22% | 12% | $34,053.22 | $30,183.54 | traditional |
| $10,000 | 22% | 22% | $30,183.54 | $30,183.54 | tie |
| $24,500 | 22% | 22% | $73,949.67 | $73,949.67 | tie |
| $24,500 | 22% | 32% | $64,468.94 | $73,949.67 | Roth |
Years = 20, return = 7% in every row. The engine clamps deferral at $24,500.
How this hits the stub
A traditional 10% on a $2,000 biweekly check is $200 out of gross, FIT $171.85, FICA still $153, net $1,475.15. Roth 10% would leave FIT at the no-deferral $195.85 because Roth does not shrink box 1. Confirm traditional math on the paycheck calculator.
Room against the shared cap: 401(k) $10,000 YTD → $14,500.
Traditional. $34,053.22 versus $30,183.54 on a $10,000 / 20-year / 7% run.
Roth. $24,500 at 22% now and 32% later keeps $73,949.67 in Roth against $64,468.94 traditional.
Same rate logic, different cap ($7,500). IRA income limits are out of scope on the IRA room tool.