401(k) vs Roth 401(k)

Pre-tax against Roth in the same plan — what actually differs, what does not, and the one number the decision turns on.

Your deferral form has a box marked Roth and a box marked pre-tax, and whichever you tick you get the same $24,500 ceiling and the same employer match. What moves is the year the IRS collects. My view, stated up front: if you're early in a career and nowhere near your peak salary, tick Roth. The rest of this page is why, and where that stops being true.

Two rows differ, and the rows people expect to differ don't

Look at the two rows people expect to be different and aren't. There's one limit, shared. There's no income test on either side. A Roth IRA phases out as income climbs; a Roth 401(k) never does, and for a well-paid employee that often makes it the one Roth account they can fund through payroll with no workaround. How the two Roth accounts compare is its own page.

The whole choice is a bet on your retirement tax rate

Strip everything else away. One question is left. Will your marginal federal rate in retirement be higher or lower than the one the IRS charges you today?

• Lower later: traditional wins, because you skipped tax at the higher rate and pay it at the lower one.
• Higher later: Roth wins, because you paid at today's lower rate and never pay again.
• The same: a dead heat. Taxing a sum and then growing it, or growing it and then taxing it, is one multiplication written in a different order.

That third line deserves a pause, because most articles on this subject assume Roth is better and never say why. Every argument for one side comes from the rates differing, or from the second-order effects further down this page.

If the rates match, a Roth 401(k) and a pre-tax 401(k) tie to the cent.

Nobody knows their future rate, and I'd distrust anyone who claims to.

Form a view anyway. Refusing to is itself a choice, and it hands the decision to whatever box your plan ticked on your behalf at enrolment.

Mine is that early in a career you should take Roth, and I'll defend it. Someone in their first or second job on a modest salary is paying close to the lowest marginal rate they will ever pay, and tax bought at that rate is the cheapest tax available to them for the rest of their life. Every pay rise makes the deduction worth more and the Roth worth relatively less. So the argument runs out somewhere around peak earnings, where you're deducting at your highest rate and expect to retire on less, and from there traditional is the better side.

Where I'd be wrong is specific. If your marginal rate ends up flat across your whole working life and into retirement, those early Roth years bought you nothing at all, and they were the years you had the least money to spare. That's a real cost and it isn't hypothetical. The Roth versus traditional 401(k) calculator takes both rates as inputs and reports a break-even, which is the retirement rate at which the two finish level, so you can see how far your own guess sits from that line.

Three things tilt the answer even when the rates tie

If the rates were the only factor, pre-tax and Roth would be a coin toss. They aren't. Each of these leans a different way.

Roth shelters more per dollar of limit. $24,500 in a Roth 401(k) is $24,500 you'll never pay tax on, while the same figure on the pre-tax side has a tax bill attached and is worth less than the statement says. For someone who fills the limit every year, Roth quietly fits more real money under the same ceiling.

Traditional needs the saving invested. The deduction is the entire case for pre-tax, and if it goes on groceries the case evaporates. Most free comparisons drop the saving altogether, which makes traditional look worse than it is and Roth better; the calculator on this site puts it in a taxable side account and taxes the growth. (That's the reason the calculator disagrees with the other tools ranking for the same search, and the reason I trust it more.)

Roth has no required distributions. Since 2024 a Roth 401(k) has had none, so nothing is forced out at 73 or 75 and nothing is forced into your taxable income in a year you didn't choose. That matters more than it sounds. Extra income late in life can pull more of your Social Security into tax and trigger Medicare surcharges. Look at what a required distribution does to a pre-tax balance before you file it under details.

Splitting isn't a cop-out

Plenty of people put some in each bucket, Roth and pre-tax, and the honest reason has nothing to do with optimising anything. Nobody can know that number.

Hold both and in retirement you get to pick which pot a given dollar comes out of. In a year when one more dollar of taxable income would cross a bracket or trip a Medicare surcharge, you take it from the Roth side. That option has real value, and no single-number comparison can show it.

The five-year clock only runs on the Roth side

Pre-tax money has no holding period. Roth money does. A Roth 401(k) withdrawal is tax-free only when it's qualified, and qualified means two conditions at once: five years since your first Roth contribution to that plan, and a qualifying event, usually turning 59½.

The clock belongs to the plan, not to you. Start Roth deferrals at a new employer and a fresh five years begins, unless you bring the old balance across by direct rollover into the new plan's designated Roth account, in which case the older start date travels with it. Someone who switches to Roth deferrals a few years before retiring can reach 59½ with a balance that still isn't qualified, and that's the case where this rule bites.

Pull money out before it qualifies and the plan splits the payment pro rata between contributions and earnings. The earnings slice is taxed and normally penalised, and you can't ask for the already-taxed part on its own. Contributions-first ordering is a Roth IRA rule. A plan can't offer it even if it wanted to.

Your match is pre-tax whichever box you tick

Most plan statements list your Roth deferrals and the employer match as separate sources. They're taxed differently. That isn't a clerical quirk.

The match has always been an employer contribution made with pre-tax money, and choosing Roth for your own deferrals doesn't change that.

It sits in its own pre-tax bucket and is taxed as ordinary income when it comes out. So a Roth 401(k) that receives a match holds two tax treatments in one account, and the retirement it funds is only partly tax-free.

SECURE 2.0 lets a plan pay the match as Roth instead. The plan has to adopt that option, and if you take it the match becomes taxable income in the year it's paid, so you owe tax on money that never reached your bank account. Most plans haven't adopted it. Either way the box you tick on the deferral form has no effect on the match at all; it's the same match, and what yours is worth matters far more than which bucket it lands in.

What this page can't settle

State tax, for a start. Someone who'll retire to a state that doesn't tax retirement income has a stronger case for pre-tax than the federal arithmetic alone suggests. Whether the tax rates themselves move is beyond any calculator, and they've moved plenty before. And above $150,000 of prior-year wages the mandatory Roth catch-up rule takes the choice away for catch-up contributions specifically. That rule sits with the limits.

The biggest gap is the framing. This page compares two ways of contributing to a 401(k), Roth and pre-tax, and it says nothing about whether to contribute or how much. How the account works and how much to put in come first, and they matter more.

Frequently asked questions

What is the difference between a 401(k) and a Roth 401(k)?

Timing of the tax, nothing else. A traditional deferral leaves your pay before income tax and the whole balance is taxed when withdrawn. A Roth deferral is taxed on the way in and a qualified withdrawal is tax-free. Both sit inside the same plan with the same $24,500 limit and the same match; you're picking a tax treatment, not an account.

Is a Roth 401(k) better than a traditional 401(k)?

Neither, until you say what your retirement tax rate will be. Higher than today favours Roth, lower favours traditional, and if the two rates are identical the accounts finish level to the cent, because taxing before growth and taxing after growth is the same sum in a different order.

Should I split between pre-tax and Roth?

Yes, if you're honest about why. Splitting doesn't optimise anything. It hedges a number nobody knows. Holding both pots means that in a retirement year when one more taxable dollar would cost you on Social Security or Medicare, you can draw from the Roth side instead.

Does the employer match go into the Roth account?

Normally no. The match is an employer contribution made pre-tax, and it stays pre-tax even when every dollar you defer is Roth, so it's taxed as ordinary income on the way out. A plan can adopt the SECURE 2.0 Roth match, which makes the match taxable to you in the year it's paid, but most haven't.

Do a 401(k) and a Roth 401(k) have separate limits?

No. The $24,500 limit for 2026 covers Roth and pre-tax together, so splitting 60/40 between them buys no extra room. The only thing that differs is whether a given dollar is taxed on the way in or on the way out.

Can I switch between pre-tax and Roth?

For future contributions, yes. It's a payroll election, and most plans let you change it whenever they process changes. Money already contributed stays in the bucket it went into. Some plans also allow an in-plan conversion of an existing pre-tax balance to Roth, and that's a taxable event in the year you do it.