Roth 401(k) vs Traditional 401(k): Which One Wins at Different Income Levels

How the Two Options Actually Differ

Traditional 401(k) contributions reduce your taxable income today. If you earn $95,000 and contribute $19,500 to a traditional 401(k), your taxable income drops to $75,500. The contribution grows tax-deferred inside the account, and every withdrawal in retirement is taxed as ordinary income at whatever rate applies then. Roth 401(k) contributions do not reduce your taxable income today. That same $19,500 goes in after tax - your $95,000 income is still $95,000 for current tax purposes. But the growth inside the account and all qualified withdrawals in retirement are completely tax-free. No tax on the gains, no tax on the withdrawals, no Required Minimum Distributions during your lifetime under SECURE 2.0 rules effective since 2024. The contribution limits are identical. In 2026, the limit is $24,500 for workers under 50, $32,500 for those ages 50-59 and 64 and older, and $35,750 for the ages 60-63 window covered by the SECURE 2.0 enhanced catch-up provision. There is no income limit for Roth 401(k) contributions - unlike Roth IRA contributions, which phase out at $242,000 to $252,000 MAGI for married filers in 2026. A CEO earning $500,000 can contribute to a Roth 401(k) without restriction. One important nuance: employer matching contributions are always made pre-tax, regardless of whether the employee elects Roth contributions. An employer match on a Roth 401(k) goes into a separate traditional bucket and will be taxable when withdrawn. The Roth election only applies to the employee's own contributions.

The Break-Even Analysis at Different Income Levels

The central question in the Roth versus traditional decision is: will you pay a lower, higher, or similar tax rate on this money in retirement compared to today? The traditional wins if your rate is lower in retirement. Roth wins if your rate is equal or higher. At $60,000 in current income for a single filer, the 2026 tax calculation puts most income in the 22% bracket after the $16,100 standard deduction. A traditional contribution saves tax at 22% today. If this person retires with $50,000 in total income from Social Security and a modest IRA, their effective rate could be 12% or lower. Traditional wins - the deferral saves at 22%, withdrawals taxed at 12%. At $150,000 in current income for a married couple, contributions are partially taxed at 22% and partially at 24%. In retirement, if this couple has $120,000 from RMDs, Social Security, and other income, they are also in the 22-24% range. The rate differential is minimal. The Roth option adds value through the RMD elimination and the tax-free inheritance benefit for children. At $250,000 in current household income, contributions may land in the 24% or 32% bracket. In retirement, if this couple has accumulated $2 million or more in tax-deferred accounts, their RMDs alone at age 73 will force $75,000 or more in taxable income - potentially pushing them back into the 24% bracket or higher, plus Social Security taxation and IRMAA. They are paying 24-32% now and face 22-32% in retirement. Roth wins or breaks even, with the bonus of RMD elimination.

The SECURE 2.0 Change That Tips the Balance

The elimination of Required Minimum Distributions from Roth 401(k) accounts during the owner's lifetime - effective in 2024 under SECURE 2.0 - changed the calculus significantly. Previously, Roth 401(k) accounts were subject to RMDs, which created an annoyance and a planning complication. Rolling the Roth 401(k) to a Roth IRA at retirement avoided RMDs but added administrative steps. Now, the Roth 401(k) behaves like a Roth IRA for RMD purposes during the owner's lifetime. This means a large Roth 401(k) balance at retirement does not generate mandatory taxable income. The owner can let it compound tax-free indefinitely, draw from it strategically to manage overall tax brackets, and leave it as a tax-free inheritance to heirs. In contrast, a large traditional 401(k) balance creates an escalating mandatory taxable income stream that the owner cannot control. At $1.5 million in traditional 401(k) assets at age 73, the first-year RMD is approximately $56,600. By age 80, that mandatory withdrawal grows further. The Roth 401(k) holder with the same $1.5 million controls when and how much to withdraw - a flexibility worth real money in tax management. For high earners who expect to have substantial tax-deferred balances at retirement, shifting future contributions to Roth while still working reduces the future RMD burden. Each dollar redirected to Roth today is a dollar not subject to mandatory distribution at age 73.

The Case for Splitting Contributions

For most workers, the most practical answer is not a binary all-Roth or all-traditional choice, but a split that builds both types of assets simultaneously. Tax diversification - having balances in both pre-tax and Roth accounts - provides flexibility in retirement. In a low-income year, draw from the traditional account to use up low-bracket space. In a high-income year when traditional withdrawals would push you into a higher bracket, draw from the Roth account instead. The optionality of having both types is worth more than the mathematical optimum of choosing one. A practical framework: if your current marginal rate is 22% or below, lean toward Roth contributions. If your marginal rate is 32% or above and you expect a significantly lower rate in retirement, lean traditional. If your marginal rate is 24% or you are uncertain about retirement income levels, split contributions - half traditional, half Roth - and build both buckets. Starting in 2026, employees who earned over $150,000 in the prior calendar year must make catch-up contributions as Roth - the IRS no longer allows pre-tax catch-up contributions for these higher earners. This mandatory Roth requirement for high-income catch-up contributors effectively resolves the Roth versus traditional question for that portion of their savings.