The choice usually arrives at an awkward moment. You are setting up a retirement plan at a new job. A screen asks whether your contributions go to the traditional side or the Roth side. There is a help link. The help link explains almost nothing.

Most people pick one and move on. That is a fair response to a confusing screen. Still, the choice is worth a few minutes, because the two accounts are far more alike than they look.

They can hold the same investments. They share the same contribution limits. They grow the same way. One thing differs between them, and it is the timing of the tax.

The one thing that actually differs

A traditional contribution is not taxed on the way in. It comes out of your pay before income tax is applied, so your taxable income for the year drops. The money then grows untouched. Later, every dollar you withdraw in retirement is taxed as ordinary income. IRS Publication 590-B states it plainly: distributions from a traditional IRA are taxed as ordinary income.

A Roth contribution is the mirror image. It is made with money that has already been taxed, so there is no deduction now. The growth is never taxed. A qualified withdrawal in retirement comes out tax-free.

Deduct now and pay later. Or pay now and be done. That is the entire difference.

Everything else people argue about follows from that one split.

The arithmetic, run both ways

Numbers make this clearer than words do.

Take $1,000 of earnings and a 22 percent marginal rate. Marginal rate means the rate on your next dollar of income, not your average rate. Assume the money triples before retirement.

The traditional path: the full $1,000 goes in, because none of it was taxed. It triples to $3,000. You withdraw it and pay 22 percent, which is $660. You keep $2,340.

The Roth path: you pay the 22 percent first, which is $220. The remaining $780 goes in. It triples to $2,340. You withdraw it and pay nothing. You keep $2,340.

The same figure, twice. This is not a coincidence or a rounding accident. Multiplication does not care about order. Taxing before growth and taxing after growth give the same answer when the rate is the same at both ends.

That result surprises people. It is worth sitting with, because it clears away most of the noise around this question. Tax-free growth is not the advantage it is often described as. Both accounts shelter growth. Only the timing of the tax bill is in dispute.

What happens when the rates differ

Since the rate is the only variable that matters, the comparison turns entirely on whether your rate changes.

Run the same $1,000 again. Suppose your rate in retirement is 12 percent rather than 22 percent. The traditional account holds $3,000 and gives up 12 percent, leaving $2,640. The Roth still leaves $2,340. The traditional side comes out $300 ahead.

Now suppose the rate in retirement is 32 percent. The traditional $3,000 gives up 32 percent, leaving $2,040. The Roth still leaves $2,340. The Roth side comes out $300 ahead.

So the question is not really about the accounts. It is about one comparison: your marginal rate now against your marginal rate in retirement.

That comparison cannot be made with certainty. Your future income is unknown. Your future filing status is unknown. Future tax law is unknown. The 2026 brackets run from 10 percent to 37 percent, with the 22 percent bracket for a single filer starting at $50,400 of taxable income, according to the IRS 2026 inflation adjustments. Those thresholds move every year, and Congress rewrites the structure itself from time to time.

Anyone who tells you which account wins is making a forecast about tax policy decades out.

Equal dollars in are not equal contributions

There is a wrinkle the arithmetic above hides.

The example started with $1,000 of pre-tax earnings and split it correctly. Real life usually starts with a contribution box on a form. If you put $7,500 into a traditional IRA and someone else puts $7,500 into a Roth IRA, those are not the same sacrifice. The Roth contribution required more earnings to fund, because the tax was already paid on it.

Put another way, a dollar in a Roth account is worth more than a dollar in a traditional account. It has no tax bill attached.

This matters most for people contributing at the annual limit. At the limit, the Roth version shelters more real money, because the contribution cap is stated in after-tax dollars for one account and pre-tax dollars for the other.

The 2026 limits, in both flavours

Both account types come in a workplace version and an individual version.

Workplace plans

The IRS sets the 2026 elective deferral limit for 401(k), 403(b) and most governmental 457 plans at $24,500. People aged 50 and over can add a catch-up contribution of $8,000. For those aged 60 through 63, the catch-up is $11,250 instead.

That single limit covers traditional and Roth deferrals combined. Splitting contributions between the two sides is allowed in most plans, but the total is capped at one figure. There is no income limit on Roth contributions inside a workplace plan.

IRAs

The 2026 IRA limit is $7,500, with an additional $1,100 for people aged 50 and over. Again, that is the combined cap across traditional and Roth IRAs, not a limit per account.

Where income starts to matter

Roth IRAs phase out at higher incomes. For 2026, the ability to contribute phases out between $153,000 and $168,000 of modified adjusted gross income for single filers and heads of household, and between $242,000 and $252,000 for married couples filing jointly. Above the top of the range, direct Roth IRA contributions are not available.

Traditional IRAs have a different kind of income test. Anyone with earned income can contribute, but the deduction can be limited. The IRS notes that the deduction is allowed in full if neither you nor a spouse is covered by a retirement plan at work. If you are covered by a workplace plan, the 2026 deduction phases out between $81,000 and $91,000 for single filers, and between $129,000 and $149,000 for married couples filing jointly.

A traditional IRA contribution that is not deductible loses the very feature that defines the account. That is worth checking before assuming the deduction is there.

The five-year rule and getting money out

Roth money is tax-free only when the withdrawal is qualified. Two conditions apply.

The first is the five-year rule. The account has to have been open for five tax years, counting the year of the first contribution. The second is age. The withdrawal generally has to happen at or after age 59½, or because of disability or death.

The clocks are separate. A designated Roth account in a 401(k) runs its own five-year period, distinct from a Roth IRA's. Opening a Roth IRA early, even with a small amount, starts that clock running.

Contributions to a Roth IRA are treated differently from earnings. The money you put in was already taxed, so it can generally come back out without tax or penalty at any time. Earnings are the part the rules restrict.

On the traditional side, withdrawals before 59½ are generally taxed and hit with an additional 10 percent tax, with a list of exceptions.

Withdrawals in the other direction differ too. Traditional accounts carry required minimum distributions starting at age 73, and those amounts are taxed at your ordinary rate. Roth IRAs have no required distributions during the owner's lifetime, and since 2024 the same is true of Roth accounts inside workplace plans, according to the IRS distribution rules.

The number on a traditional statement is not the number

A traditional balance of $400,000 is not $400,000 of spendable money. It is $400,000 minus a future tax bill at a rate nobody has set yet.

The statement does not show that. It cannot, because the rate is unknown. So two people with identical balances, one traditional and one Roth, do not have identical wealth. The Roth holder owns their whole balance. The traditional holder owns a balance and an unpriced liability.

None of this makes the traditional account worse. The deduction taken years earlier was real money, and it may well have been invested too. It just means the two statements are not directly comparable, and the gap between them is genuinely unknown until the money comes out.

What pushes the comparison each way

Certain situations tend to shift the balance, without settling it.

• Early career, low bracket. Someone in the 12 percent bracket early on has a decent chance of facing a higher rate later. Paying tax at today's known low rate is what the Roth side offers.
• Peak earning years. Someone in the 32 or 35 percent bracket is deducting at a high rate, and retirement income is often lower than working income. That leans toward the traditional side.
• Already retired thinking. Pensions, rental income, Social Security and required distributions can push retirement income higher than expected. People who anticipate that sometimes lean Roth despite a high current rate.
• Not knowing. Holding both is a hedge. Money in each type gives you some ability to choose which account to draw from, and therefore some control over taxable income in a given year. That flexibility is often called tax diversification.

The last one deserves attention, because it is the only response that does not require a forecast. Splitting contributions is not indecision. It is a reasonable answer to a question that has no knowable answer.

The honest summary is short. If your rate is the same at both ends, the two accounts produce the same result. If it is lower later, the traditional side wins. If it is higher later, the Roth side wins. Which of those turns out to be true depends on your income decades from now and on tax law that has not been written.

References and sources

• Internal Revenue Service, 401(k) limit increases to $24,500 for 2026, IRA limit increases to $7,500 — source of the 2026 elective deferral limit, catch-up amounts, IRA limit, and the Roth IRA and traditional IRA deduction phase-out ranges.
• Internal Revenue Service, IRS releases tax inflation adjustments for tax year 2026 — source of the 2026 marginal rate brackets referenced in the rate comparison.
• Internal Revenue Service, Publication 590-B, Distributions from Individual Retirement Arrangements — treatment of traditional IRA distributions as ordinary income, and the Roth qualified distribution rules.
• Internal Revenue Service, IRA deduction limits — when a traditional IRA contribution is fully deductible and when workplace plan coverage limits it.
• Internal Revenue Service, Retirement topics: designated Roth account — the five-year rule and age conditions for Roth accounts inside workplace plans.
• Internal Revenue Service, Retirement plan and IRA required minimum distributions FAQs — the age 73 start for required distributions and the Roth exemption during the owner's lifetime.
• Internal Revenue Service, Topic no. 557, Additional tax on early distributions — the 10 percent additional tax before age 59½ and its exceptions.

This article is educational. It does not represent financial, tax, legal, accounting or investment advice. Consult the appropriate qualified professional advisors before acting on its contents.