Roth 401(k) vs. Traditional 401(k): Which Should You Choose?

The Core Difference

| Feature | Traditional 401(k) | Roth 401(k) | | :--- | :--- | :--- | | Contributions | Pre-tax (reduces taxable income now) | After-tax (no immediate tax break) | | Growth | Tax-deferred | Tax-free | | Withdrawals in retirement | Taxed as ordinary income | Completely tax-free | | Best for | High earners in peak tax bracket | Young workers expecting higher future income |

How the Math Works

Consider two workers, both 25, earning $50,000, contributing $5,000/year for 40 years at 7% growth:

Traditional 401(k)

• Contribution: $5,000 pre-tax (reduces taxable income)
• Tax savings now: ~$1,100/year (at 22% bracket)
• At retirement: ~$1,000,000 in account
• Tax on withdrawals: ~$220,000 (at 22% bracket)
• After-tax value: ~$780,000
• Source: Finance4Everyone calculation using IRS tax bracket data.

Roth 401(k)

• Contribution: $5,000 after-tax (no immediate tax break)
• At retirement: ~$1,000,000 in account
• Tax on withdrawals: $0
• After-tax value: ~$1,000,000
• Source: Finance4Everyone calculation.

The difference: $220,000 in retirement. However, this is a simplified model; the optimal choice depends on your current marginal tax rate versus your expected marginal tax rate in retirement.

When to Choose Traditional

Choose traditional 401(k) when:

• You're in your peak earning years: Your current tax bracket is higher than it will be in retirement.
• You need the tax break now: The immediate deduction helps manage current cash flow.
• You expect lower income in retirement: A lower tax bracket in retirement results in less tax paid on withdrawals.

When to Choose Roth

Choose Roth 401(k) when:

• You're young and early in your career: Your income and tax bracket will likely rise, making tax-free withdrawals more valuable later.
• You expect higher taxes in the future: If tax rates increase over time, paying taxes now at a lower rate is advantageous.
• You want tax diversification: Having both traditional and Roth accounts provides flexibility to manage your taxable income in retirement.

The Power of Tax-Free Growth

The Roth advantage compounds over time. Every dollar of investment growth in a Roth account is permanently tax-free, provided the distribution is "qualified"—generally meaning you are at least age 59½ and the account has been open for at least five years.

| Years Invested | $5,000/Year at 7% | Tax-Free Growth | | :--- | :--- | :--- | | 10 | $69,000 | $19,000 | | 20 | $205,000 | $105,000 | | 30 | $472,000 | $322,000 | | 40 | $1,000,000 | $800,000 |

Source: Finance4Everyone calculation.

Can You Have Both?

Yes. Many plans allow you to split contributions between traditional and Roth ^[1]. This provides tax diversification—you will have some assets that are tax-free (Roth) and some that are taxed as ordinary income (traditional), giving you more control over your tax liability in retirement ^[2]. For 2026, the total annual elective deferral limit for 401(k) plans is $24,500 (or $32,000 if age 50 or older, including catch-up contributions) ^[4], ^[9]. If you are just starting to plan your savings, use our Compound Interest Calculator to see how these contributions grow over time.

Key Takeaway

• Traditional 401(k): Provides a tax break now; withdrawals are taxed as ordinary income in retirement.
• Roth 401(k): No tax break now; qualified withdrawals are tax-free in retirement.