Deciding Between Types of 401(k)s

For most employees, deciding between types of 401(k)s is not a choice between two different investment programs. It is a choice about how contributions inside the same workplace retirement plan will be taxed. Traditional 401(k) contributions generally give you a tax break now and create taxable income when the money is withdrawn later, while Roth 401(k) contributions are included in taxable income now and can produce tax-free qualified withdrawals in retirement.

That trade-off sounds simple, but the useful comparison is not merely “tax now” versus “tax later.” The better choice depends on the marginal tax rate you avoid today, the tax rates that may apply to future withdrawals, how much you can afford to save after tax, what other retirement income you expect, and how much flexibility you want over taxable income later. A worker may also use both tax treatments, so the decision does not need to be all-or-nothing.

Traditional and Roth are tax choices inside a 401(k)

A 401(k) plan is an employer-sponsored defined contribution plan. Many plans let employees direct salary deferrals to a traditional pre-tax account, a designated Roth account, or both, while the employer determines the investment menu and other plan features. The Roth and traditional labels describe the tax treatment of money inside the plan rather than a fundamentally different set of investments.

Traditional salary deferrals generally reduce federal taxable income in the year of contribution. The money and its investment earnings remain tax-deferred inside the plan, and taxable distributions are generally included in ordinary income when withdrawn. Roth salary deferrals do not reduce current taxable income, but qualified distributions of Roth contributions and earnings are tax-free.

For 2026, the basic employee elective-deferral limit for most 401(k) plans is $24,500. Traditional and Roth salary deferrals share that limit, so contributing $14,500 to the traditional side and $10,000 to the Roth side would use the full $24,500 employee limit. Eligible participants age 50 or older can generally make an additional $8,000 catch-up contribution in 2026, and participants who turn 60, 61, 62 or 63 during the year have a higher $11,250 catch-up limit for most 401(k) plans.^[1]

The tax choice is separate from other 401(k) plan categories that employers and business owners may encounter, such as safe harbor 401(k)s, SIMPLE 401(k)s and one-participant or solo 401(k)s. Those terms describe plan design and eligibility features. An employee comparing pre-tax and Roth salary deferrals should first focus on the tax treatment offered by the specific plan in front of them.

Start with your current and future marginal tax rates

The most important comparison is the marginal tax rate saved on a traditional contribution today versus the marginal rate likely to apply when that dollar and its earnings eventually come out of the account. A traditional contribution is more valuable when it shelters income that would otherwise be taxed at a relatively high rate today and the eventual withdrawal is taxed at a lower rate. Roth becomes more attractive when the tax paid today is relatively low and future withdrawals would otherwise face a higher rate.

The phrase “tax rate in retirement” can be misleading because retirement income is rarely taxed at one single rate. Traditional 401(k) withdrawals may sit on top of Social Security benefits, pensions, wages from part-time work, investment income and other taxable sources. Some of the withdrawal may fall into a lower bracket and some may fall into a higher one, so a sensible comparison considers the marginal rate on the next dollar rather than simply comparing current salary with expected retirement spending.

Compare marginal rates, not average rates

Suppose a worker is in a 24% federal marginal bracket and can make a $10,000 traditional contribution. Ignoring state taxes, the contribution reduces current federal income tax by about $2,400, so the reduction in take-home pay is roughly $7,600. A Roth contribution that creates the same $7,600 reduction in take-home resources would be $7,600 because there is no current deduction for the Roth contribution.

If both amounts later double and the future marginal tax rate is also 24%, the traditional account grows to $20,000 and leaves $15,200 after a 24% tax, while the Roth grows from $7,600 to $15,200 and a qualified withdrawal is tax-free. With equal tax rates and equal after-tax saving effort, the two approaches are economically similar. If the future marginal rate is 12%, the traditional account would leave $17,600 after tax and come out ahead in this simplified example, while a 32% future rate would leave $13,600 and make the Roth treatment more valuable.

Why equal account contributions are not an equal-cost comparison

The comparison changes when someone contributes the same nominal amount to each account rather than holding current cash flow constant. A $10,000 Roth contribution costs more in current take-home pay than a $10,000 traditional contribution because the Roth saver also pays income tax on the earnings used for the contribution. The Roth account therefore represents more after-tax wealth when the two account balances are the same.

This matters especially for workers who can reach the employee contribution limit. Maxing out a Roth 401(k) effectively places more after-tax purchasing power behind the 401(k) tax shelter than maxing out a traditional 401(k), but it also requires enough current cash flow to pay the tax bill outside the account. A fair comparison should account for what happens to the tax savings created by the traditional contribution. If those savings are invested elsewhere, the traditional strategy has an additional asset that should not be ignored.

When traditional contributions deserve more weight

Traditional contributions are often attractive during peak earning years, particularly when each additional dollar of taxable income is being taxed at a high marginal rate. A worker who expects lower taxable income after leaving full-time work may prefer to take the deduction while it is expensive to earn the next dollar and pay tax later when withdrawals can be managed within lower brackets. The value is strongest when the current deduction clearly saves tax at a higher rate than the expected future withdrawal rate.

Current cash flow also matters. Because a traditional contribution reduces current taxable income, it usually causes a smaller decline in take-home pay than the same nominal Roth contribution. Someone trying to increase retirement saving without putting too much pressure on the monthly budget may therefore be able to contribute more on a pre-tax basis than on a Roth basis, although the eventual tax liability means the balances should not be viewed as equivalent dollar for dollar.

State income taxes can reinforce the case for traditional contributions when a worker lives in a relatively high-tax state now and reasonably expects to retire in a jurisdiction with lower taxes. The opposite move can favor Roth. State tax rules differ and can change, so this is a planning factor rather than a reason to make a permanent assumption decades in advance.

A traditional contribution can also be useful in a year when taxable income temporarily jumps because of a bonus, equity compensation, unusually high self-employment income or another one-off event. Using more pre-tax contribution room in a high-income year and more Roth contribution room in a lower-income year can be more defensible than choosing one tax treatment for an entire career.

When Roth contributions deserve more weight

Roth contributions tend to be more attractive when the current marginal tax rate is relatively low. Early-career workers, people who have temporarily reduced hours, households with unusually large deductions, and workers between higher-income periods may be paying tax on the next dollar at a rate that is difficult to improve on later. Paying tax at that lower rate can purchase years of tax-free qualified growth inside the Roth account.

A long time horizon alone does not automatically make Roth better, because traditional contributions also compound without annual tax on investment earnings. The important issue is the tax rate applied at the beginning versus the tax rate applied at withdrawal. Time magnifies the amount in either account, but it does not by itself reverse the underlying tax-rate comparison.

Roth can also be valuable for households that expect substantial taxable retirement income from pensions, traditional IRAs, traditional 401(k)s or other sources. Building a pool of qualified Roth money gives the household a source of spending that does not add taxable income when withdrawn. That flexibility can be useful in years when taking additional taxable distributions would push more income into a higher bracket or otherwise interfere with a tax plan.

Tax law is another source of uncertainty. No one can know today what federal or state tax rates will be decades from now, and a worker’s income path can change just as much as the tax code. Roth contributions do not eliminate that uncertainty, but having some assets that can be withdrawn tax-free under current law reduces dependence on one future tax regime.

Using both traditional and Roth can be rational

Many plans allow participants to split salary deferrals between traditional and Roth sources, subject to the same combined employee limit. A split can make sense when the tax-rate comparison is close, when future income is difficult to forecast, or when the saver already has a large concentration in one tax type. There is no rule that the split needs to be 50-50, and the best mix can change from one year to the next.

Tax diversification has a practical purpose rather than simply being diversification for its own sake. Retirees with both traditional and Roth balances have more control over which account funds a particular year’s spending. Traditional withdrawals can be used while taxable income is low, while Roth withdrawals can cover additional spending without creating the same federal taxable income when the Roth distribution is qualified.

A worker who already has decades of pre-tax contributions may reasonably direct new money toward Roth even if the current and expected future tax rates look similar. Another worker with a large Roth balance and a high current marginal rate may benefit more from new traditional contributions. Looking at the household’s existing retirement accounts often gives a better answer than treating each year’s contribution decision in isolation.

Employer match and plan rules can change the details

Choosing Roth for your own salary deferrals does not normally mean giving up an employer match. Employers can match designated Roth salary deferrals just as they can match traditional deferrals, although the plan’s matching formula and eligibility rules still control how much is contributed. The older idea that an employer can never put money on the Roth side is no longer accurate.

Under SECURE 2.0, a plan may allow certain fully vested employer matching and nonelective contributions to be designated as Roth contributions. If the plan does not offer that feature, employer contributions may still go into a pre-tax source even when the employee makes Roth salary deferrals, so a participant can end up with both tax treatments automatically. Designated Roth contributions are included in current gross income, while qualified distributions from the Roth account can be tax-free.^[2]

Plan documents matter because not every employer offers every feature. Some plans may allow Roth contributions but not Roth treatment for employer contributions, and some may place restrictions on contribution changes during the year. Participants should also check the vesting rules for employer money, because their own salary deferrals are always fully vested but some employer contributions can be subject to a vesting schedule.

For 2026, the catch-up rules also add a new plan-specific wrinkle for some higher-paid workers. The IRS states that participants in plans with Roth features who are subject to the Roth catch-up requirement must make catch-up contributions on a Roth basis when their prior-year wages with the plan sponsor exceed the applicable $150,000 threshold for 2026. That rule does not change the traditional-versus-Roth choice for the basic employee deferral, but it can limit the tax treatment available for the catch-up portion.

Withdrawal rules matter, but age 59½ is not the whole story

The old shorthand that Roth money becomes completely unrestricted at age 59½ is too broad. A distribution from a designated Roth 401(k) is generally tax-free only when it is a qualified distribution, which normally requires both a five-taxable-year participation period and a qualifying event such as reaching age 59½, death or disability. If the five-year requirement has not been met, the distribution can be nonqualified even after age 59½, and the earnings portion can receive different tax treatment.

Traditional 401(k) distributions are generally taxable because the salary deferrals and investment earnings were not previously taxed. Distributions before age 59½ can also face the 10% additional tax unless an exception applies. The precise early-withdrawal rules deserve separate attention because exceptions can depend on why the money is being taken, whether employment has ended, and the type of account receiving a rollover.

Roth 401(k) rollovers are useful but should not be treated as a magic reset button. A designated Roth account can generally be rolled to another designated Roth account or to a Roth IRA, while pre-tax 401(k) money can generally be rolled to another eligible pre-tax retirement account without current tax. Moving pre-tax money to Roth is a conversion and generally makes the previously untaxed amount taxable in the year of conversion, so rollover and conversion decisions should be kept separate from the basic contribution choice.

RMDs no longer put Roth 401(k)s at the old disadvantage

One of the biggest factual changes since the original version of this article is the treatment of required minimum distributions. Designated Roth accounts in qualified employer plans are no longer subject to lifetime RMDs for the original owner, bringing them closer to Roth IRAs on this point. Traditional 401(k) balances remain subject to RMD rules when the applicable starting requirements are met, although a current employee who is not a 5% owner may be able to delay RMDs from that employer’s plan until retirement depending on the circumstances.^[3]

The removal of Roth 401(k) lifetime RMDs weakens an argument that used to favor rolling a Roth 401(k) to a Roth IRA simply to avoid forced distributions. A rollover may still make sense for investment choice, fees, account consolidation, beneficiary planning or other reasons, but the old Roth 401(k) RMD disadvantage is no longer a current reason by itself.

Do not let the tax choice distract from the plan itself

Traditional versus Roth is important, but it is only one part of using a workplace plan well. The value of an employer match, the quality and cost of the available investments, the plan’s administrative fees, vesting rules and the amount you can afford to contribute can matter more than a modest difference between two uncertain future tax rates. A theoretically perfect tax choice cannot compensate for failing to capture a valuable employer match or for saving far too little.

The investment allocation deserves separate treatment from the tax decision. A Roth 401(k) invested in an unsuitable portfolio is not automatically better than a traditional 401(k) invested sensibly, and the reverse is equally true. After choosing how contributions will be taxed, retirement investing and saving should still be guided by time horizon, risk and portfolio construction on their own merits.

Workers comparing a 401(k) with an IRA face another decision entirely. An IRA can provide a different investment menu and different withdrawal rules, while a 401(k) may provide an employer match, higher contribution capacity and plan-specific protections. Those trade-offs are better evaluated separately rather than using a preference for Roth or traditional taxation to decide automatically between account types.

Make the choice with taxes, cash flow and flexibility in view

A useful starting point is to identify the marginal tax rate a traditional contribution would save today, then estimate the range of marginal rates that could apply to future traditional withdrawals. The estimate does not need to be perfect. It should account for pensions, Social Security, other retirement accounts, likely state residence and any years in which retirement income may be unusually low or high.

Next, compare the two options on an equal economic basis. If you are comparing a $10,000 traditional contribution with a $10,000 Roth contribution, remember that the Roth requires more current after-tax resources. If you are comparing equal reductions in take-home pay, the Roth contribution will be smaller than the traditional contribution at positive tax rates, and the traditional strategy’s current tax savings should be included in the analysis rather than assumed to disappear.

Workers who see a clear tax-rate advantage can lean toward the account that captures it. Workers facing close calls or substantial uncertainty can use both, revisiting the mix as income, tax law and retirement balances change. The decision is best treated as an annual planning choice rather than a permanent identity, and contributing enough to build a durable retirement plan is usually more important than trying to forecast the tax code with false precision.