Pre-Tax vs Roth vs After-Tax 401(k) Calculator 2026 β 3-Way Comparison
Compare pre-tax 401(k), Roth 401(k), and after-tax mega backdoor Roth. 2026 limits: $24,500 employee deferral, $70,000 total. Shows current tax savings, future after-tax wealth, and optimal allocation by income and tax bracket.
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E.g. 4% = 100% match on first 4%
Reduces taxable income now
No deduction, tax-free at retirement
Converts to Roth via in-plan conversion
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Total Annual Contribution (all buckets)
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Current Year Tax Savings (pre-tax)
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Total Future Value at Retirement
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After-Tax Wealth at Retirement
3-Way 401(k) Comparison β 2026
| Bucket | Annual Contribution | Current Tax Savings | Future Value | After-Tax Retirement Value |
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Pre-Tax vs Roth vs After-Tax 401(k) β 2026 Guide
The three 401(k) contribution buckets have fundamentally different tax structures. Understanding when each is optimal requires comparing your current tax rate vs your expected retirement tax rate, your investment time horizon, and whether your plan allows after-tax contributions.
2026 Contribution Limits
Employee elective deferral (pre-tax + Roth combined): $24,500
Catch-up age 50-59 & 63-64: +$7,500 = $32,000 total
Special catch-up age 60-63 (SECURE 2.0): +$11,250 = $35,750 total
Total 415(c) limit (employee + employer): $70,000 ($77,500 with catch-up)
After-tax space = $70,000 β employee deferrals β employer contributions
SS Wage Base 2026: $184,500 | Medicare: all wages | Add\'l Medicare: $200K+
Catch-up age 50-59 & 63-64: +$7,500 = $32,000 total
Special catch-up age 60-63 (SECURE 2.0): +$11,250 = $35,750 total
Total 415(c) limit (employee + employer): $70,000 ($77,500 with catch-up)
After-tax space = $70,000 β employee deferrals β employer contributions
SS Wage Base 2026: $184,500 | Medicare: all wages | Add\'l Medicare: $200K+
The Break-Even Rule
Pre-tax beats Roth when: Current Rate > Retirement Rate
Roth beats Pre-tax when: Current Rate < Retirement Rate
Equal (ignoring growth) when: Current Rate = Retirement Rate
In practice: Roth advantage grows with longer time horizon (more tax-free compounding).
After-tax mega backdoor converts to Roth β similar to Roth but allows much higher amounts.
Roth beats Pre-tax when: Current Rate < Retirement Rate
Equal (ignoring growth) when: Current Rate = Retirement Rate
In practice: Roth advantage grows with longer time horizon (more tax-free compounding).
After-tax mega backdoor converts to Roth β similar to Roth but allows much higher amounts.
Extended
Optimal Allocation Strategy + After-Tax Wealth at Retirement
Year-by-year growth comparison, break-even tax rate analysis, and allocation recommendations by bracket and time horizon
After-Tax Wealth Comparison β All 3 Buckets Over Time
| Year | Pre-Tax After-Tax Value | Roth After-Tax Value | After-Tax/Roth Value | Best Bucket |
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Break-Even Retirement Tax Rate Analysis
| Retirement Tax Rate | Pre-Tax After-Tax Wealth | Roth After-Tax Wealth | Winner |
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Frequently Asked Questions
What are the 2026 401(k) contribution limits?
For 2026: The employee elective deferral limit is $24,500 for pre-tax and Roth contributions combined (up from $23,500 in 2025). The catch-up contribution for age 50-59 and 63-64 is $7,500 (total $32,000). Special catch-up for ages 60-63 under SECURE 2.0 is $11,250 (total $35,750). The total 415(c) limit β covering employee contributions (pre-tax + Roth + after-tax) plus employer match/profit sharing β is $70,000 ($77,500 with standard catch-up). The after-tax contribution space is the difference between $70,000 total and your elective deferrals plus employer contributions, enabling the "mega backdoor Roth" strategy.
What is the mega backdoor Roth and how does it use after-tax 401(k) contributions?
The mega backdoor Roth is a strategy that uses the gap between the $70,000 total 401(k) limit and the $24,500 elective deferral limit. If your employer's plan allows after-tax contributions AND in-service withdrawals or in-plan Roth rollovers, you can: (1) contribute up to ~$45,500 in after-tax dollars (the difference after your deferrals and employer match), then (2) immediately convert to Roth (in-plan conversion or roll to Roth IRA). The after-tax contributions have no income limit, the conversion typically has minimal taxable gain if done promptly, and future growth is permanently tax-free. Not all plans allow this β check your SPD.
When is pre-tax 401(k) better than Roth 401(k)?
Pre-tax (traditional) 401(k) is generally better when: (1) your current tax rate is higher than your expected retirement tax rate, (2) you expect to withdraw in lower-income years, (3) you need the current-year tax deduction to reduce another tax burden (like IRMAA or child tax credit phase-outs), or (4) you are in the 32%+ bracket and expect to be in the 22-24% bracket in retirement. Roth is generally better when: (1) you are currently in a low bracket (10-22%) and expect higher rates later, (2) you have decades of tax-free growth, (3) you want to avoid RMDs (Roth 401k RMDs eliminated under SECURE 2.0 starting 2024), or (4) you expect higher tax rates broadly.
What happens to after-tax 401(k) contributions if my plan does NOT allow in-service withdrawals?
Without in-service withdrawals, after-tax contributions sit in the plan until separation from service (termination, retirement, etc.). Upon distribution, only the earnings on after-tax contributions are taxable β the basis (the after-tax contributions themselves) comes out tax-free. However, the earnings are taxable as ordinary income (unlike a converted Roth which would be tax-free after 5 years). To execute the mega backdoor Roth without in-service withdrawals, you need an in-plan Roth conversion feature β many modern 401(k) plans offer this as an alternative to in-service withdrawal.
Do Roth 401(k) accounts have income limits for contributions?
No. Unlike Roth IRA contributions (which phase out at $165,000β$175,000 single and $246,000β$256,000 MFJ for 2026), Roth 401(k) contributions have no income limits whatsoever. This makes the Roth 401(k) a valuable tool for high earners who cannot contribute to a Roth IRA directly. High-income individuals ($200K+) who want Roth savings can contribute up to $24,500 to Roth 401(k) plus potentially do a mega backdoor Roth, regardless of their income level.