This article summarizes general US retirement account rules for informational purposes.

It is not financial or tax advice — the right choice depends on your income, tax bracket, and expectations about the future, and should be discussed with a financial advisor or tax preparer familiar with your full situation.

Key Takeaways

The 2026 employee contribution limit is $24,500 for either a traditional or Roth 401(k), or split between both — the cap is combined, not doubled, if your plan offers both options.
A traditional 401(k) contribution reduces your taxable income this year; a Roth 401(k) contribution doesn't, but qualified withdrawals in retirement come out completely tax-free.
Workers age 50 to 59 or 64 and older can add a $8,000 catch-up contribution in 2026, while those aged 60 to 63 get an enhanced $11,250 catch-up under SECURE 2.0 — on top of the $24,500 base limit.
Starting in 2026, a new rule requires catch-up contributions to be made as Roth, not traditional, for anyone who earned $150,000 or more in FICA wages the prior year — a mandatory shift that limits the pre-tax option specifically for higher-earning older workers.
Employer matching and profit-sharing contributions always land in a traditional, pre-tax account, regardless of which type you personally choose to contribute to — there's no such thing as an employer Roth match.

The core trade-off, in one sentence

Every dollar you put into a traditional 401(k) skips tax now and gets taxed later, on withdrawal, at whatever your ordinary income tax rate happens to be in retirement. Every dollar you put into a Roth 401(k) gets taxed now, at today's rate, and then grows and comes out completely untouched by tax later, as long as the withdrawal is qualified — meaning the account has been open at least five years and you're 59½ or older, disabled, or the withdrawal follows your death.

That's the whole decision, reduced to its essence: are you betting your tax rate will be higher now, or higher later? If you expect to be in a lower bracket in retirement than you are today — a common assumption for someone in their peak earning years — the traditional account's upfront deduction, taken at today's higher rate, tends to come out ahead. If you expect the opposite — you're early in your career, in a lower bracket now than you'll likely be later, or you simply want tax certainty regardless of what future tax law does — the Roth's tax-free growth becomes the more attractive bet.

What the 2026 numbers actually are

The IRS 401(k) contribution limit for 2026 rose to $24,500 for employee salary deferrals, and that number applies identically whether the money goes into a traditional account, a Roth account, or gets split between the two — the cap is combined, not $24,500 for each type separately. Combined employee-plus-employer contributions can go as high as $72,000 for 2026, which matters most for anyone with a generous employer match or, notably, a self-employed person using a Solo 401(k), where the same person is contributing as both employee and employer.

Catch-up contributions add real room for older workers. Anyone 50 or older, or 64 and above, can add an $8,000 catch-up on top of the $24,500 base limit in 2026. Workers specifically aged 60 through 63 get an enhanced $11,250 catch-up instead, under a SECURE 2.0 provision aimed at that narrower pre-retirement age band — bringing their total possible employee deferral to $35,750 for the year.

The rule that quietly narrows the choice for some people

Here's a 2026-specific wrinkle worth knowing about even if you've always preferred the traditional account: starting this year, anyone who earned $150,000 or more in FICA wages during the prior year is required to make their catch-up contributions on a Roth basis — not as a choice, but as a mandatory rule under SECURE 2.0. Their regular $24,500 base contribution can still go either traditional or Roth as they prefer, but the catch-up portion specifically has to be after-tax for that income group.

This mostly affects higher-earning workers in their 50s and 60s who were counting on the catch-up amount specifically for its upfront deduction — that particular piece of the puzzle isn't optional for them anymore, regardless of which side of the traditional-versus-Roth debate they'd otherwise land on.

The one piece that's never a choice

Whatever you personally decide about your own contributions, any money your employer adds — a matching contribution, profit sharing, or any other employer-funded piece — always goes into a traditional, pre-tax account. There's no such thing as an employer contributing on a Roth basis; that money will be taxed as ordinary income when you eventually withdraw it, regardless of how you've structured your own contributions. This means nearly everyone with an employer match ends up with at least some traditional-account money in their retirement mix no matter which type they personally prefer.

What this means if you're deciding right now

If you're in a high tax bracket today and expect a meaningfully lower one in retirement, lean traditional. The deduction is worth more to you now, at your current marginal rate, than the same dollar amount of tax-free growth would likely be worth later at a lower rate.
If you're early career, in a lower bracket now, or simply skeptical that tax rates will be lower for you later, lean Roth. Paying tax at today's lower rate and locking in tax-free withdrawals removes the risk that rates — yours or the country's — rise before you retire.
If you're 60 to 63 in 2026, don't overlook the enhanced $11,250 catch-up window. It's a narrower age band than people expect, and it closes once you turn 64, reverting to the standard $8,000 catch-up amount.
If you earned $150,000+ in FICA wages last year and are 50 or older, plan for your catch-up contribution to be Roth regardless of preference. It's not a choice under the new rule, so build that into your withholding and cash-flow expectations for the year rather than being surprised by it at contribution time.

Frequently Asked Questions

Can I contribute to both a traditional and a Roth 401(k) in the same year? Yes, if your employer's plan offers both — you can split your $24,500 base contribution between the two in any combination you choose, as long as the combined total across both doesn't exceed the annual limit.

Does the Roth 401(k) have income limits like a Roth IRA does? No — this is one of the Roth 401(k)'s real advantages over a Roth IRA. High earners who are phased out of contributing directly to a Roth IRA can still make full Roth 401(k) contributions through their employer's plan, since the Roth 401(k) has no income-based eligibility restriction.

What happens to my traditional 401(k) money if I want to convert it to Roth later? Many plans allow an in-plan Roth conversion, where you move traditional 401(k) funds into a Roth 401(k) and pay ordinary income tax on the converted amount in the year of conversion. This is a separate decision from your ongoing contribution choice and is worth discussing with a tax preparer given the immediate tax bill it triggers.

Is the new mandatory Roth catch-up rule permanent, or could it change? It's current law under SECURE 2.0 as of 2026, but like any tax provision, it's set by Congress and subject to future legislative change. Higher earners affected by it should plan around current rules while staying aware that retirement account rules do shift over time.

Sources & References

Fidelity, "401(k) contribution limits 2026"
Fidelity, "Roth 401(k) contribution limits for 2026"
IRS, "401(k) limit increases to $24,500 for 2026, IRA limit increases to $7,500"
Charles Schwab, "Roth 401(k) vs. Roth IRA: What's the Difference?"
SDO CPA, "Roth 401(k) vs Traditional 401(k) 2026 | Business Owner Guide"
Birch Street Financial Advisors, "Should I Contribute to My Roth 401(k)? What Changed in 2026 and How to Decide"
NerdWallet, "Roth 401(k) vs. 401(k): Comparison and 2025-2026 Limits"

Traditional 401(k) vs Roth 401(k) in 2026: The Choice That Actually Depends on a Guess