Roth vs traditional IRA: how to compare tax now and tax later

A traditional IRA and a Roth IRA hold the same investments and share the same yearly limit. The difference is entirely about when the IRS takes its cut. A traditional IRA can give you a deduction today and taxes the money when it comes out. A Roth IRA gives no deduction today and lets qualified withdrawals, including decades of growth, come out tax-free.

That sounds like a matter of taste. It isn't. With a little arithmetic you can see exactly which conditions make one beat the other, and they come down to one comparison: your tax rate now against your tax rate when you withdraw. This guide works through that math with 2026 US federal figures, then covers who is allowed to contribute to each, the five-year rules that govern Roth withdrawals, and how Roth conversions work.

All rules here are US federal, for tax year 2026. States treat IRA contributions and withdrawals in different ways, so the state side of the comparison can tilt the result. This is education, not tax advice.

The core math: tax now or tax later

Start with a fair comparison. Suppose you have $7,500 of salary you want to save and you are in the 22% federal bracket. In a traditional IRA, if the contribution is fully deductible, the whole $7,500 goes in and you owe no tax on it this year. To put money into a Roth, you first pay 22% income tax on that salary, so the same $7,500 of pay becomes $5,850 in the account.

The example shows the rule behind every Roth-versus-traditional decision. Multiplication doesn't care about order: paying 22% before growth or 22% after growth leaves the same amount. Only a difference in rates between contribution and withdrawal changes the answer. Investment returns, account length and fund choice don't decide it; they just magnify the effect of the rate gap.

Why the comparison is rarely that tidy

Real decisions bend the clean result in a few ways.

Your marginal rate today is easy to see; your rate later is a forecast. In retirement, income might come from Social Security, pensions, required minimum distributions, part-time work and taxable accounts. Many people's taxable income falls after they stop working; some people, especially large savers, find RMDs from big traditional balances push them into higher brackets. Tax law itself can change between now and then.

The limit is the same for both, so a maxed Roth holds more. If you contribute the full $7,500 to a Roth, you have sheltered $7,500 of after-tax money, which is worth more than $7,500 in a traditional account (part of that belongs to the IRS). People who can fill the limit either way get more tax-sheltered value from the Roth at equal rates.

A deduction lowers your adjusted gross income. A lower AGI can bring you under other thresholds, such as eligibility for the Saver's Credit (for 2026, AGI up to $80,500 for a married couple filing jointly, $60,375 for a head of household and $40,250 for others). That can make a traditional contribution worth more than its marginal rate suggests.

Roth money is more flexible. Roth IRAs have no required minimum distributions for the original owner, and your contributions can come out at any time without tax or penalty. Traditional IRAs require distributions from 73, or 75 for those born in 1960 or later.

State taxes. Moving from a high-tax state to one with no income tax (or the reverse) changes the combined rate at withdrawal and can flip the answer.

Rules of thumb people use

None of these is a rule of law, just a way of applying the math:

• Early in a career, with low income now and higher expected income later, the Roth's "pay the low rate now" logic tends to look strongest.
• In peak earning years, at a high bracket, the traditional deduction tends to look strongest, especially if retirement income will be modest.
• Holding both kinds gives tax diversification: in retirement you can draw from whichever bucket keeps your taxable income in a lower bracket that year.

Who can contribute: the 2026 Roth income limits

Anyone with taxable compensation can contribute to a traditional IRA. A Roth IRA contribution, by contrast, shrinks and then disappears as modified adjusted gross income (MAGI) rises through a phase-out range.

Inside the range, the allowed contribution falls in proportion to how far you are into it. IRS Publication 590-A gives the worksheet; it rounds the result up to the next $10 and allows at least $200 if you are anywhere below the top of the range.

When a traditional IRA contribution is deductible

Contributing to a traditional IRA is always allowed with compensation; deducting it depends on whether you or your spouse is an active participant in a workplace retirement plan, and on income. If neither of you is covered, the full contribution is deductible at any income.

"Covered" generally means you were eligible for or received contributions in a workplace plan during the year, shown by the retirement-plan box on your Form W-2. Note the gap between the two tables: at $100,000 of income, a single worker with a 401(k) gets no traditional IRA deduction but can still make a full Roth contribution.

The five-year rules and how Roth withdrawals work

Roth IRAs are tax-free only for qualified distributions. A distribution is qualified when two tests are met:

1. Five years have passed since January 1 of the first tax year for which you made any Roth IRA contribution. A contribution made in April 2027 for tax year 2026 starts the clock on January 1, 2026.
2. You are 59½ or older, disabled, using up to $10,000 (lifetime) for a first home, or the money is paid to a beneficiary after your death.

Distributions that aren't qualified are not automatically taxed, because Roth withdrawals come out in a fixed order:

The second row is the second five-year rule: each conversion has its own five-year period for the 10% additional tax. It exists so that people under 59½ can't convert and immediately withdraw to dodge the early-withdrawal penalty on traditional money.

Roth conversions

A Roth conversion moves money from a traditional IRA (or a traditional 401(k), through a rollover) into a Roth IRA. The pre-tax amount you convert counts as ordinary income in the year of the conversion. In return, that money and its future growth can later come out tax-free under the qualified-distribution rules.

Key facts about conversions, as of 2026:

• No income limit. Anyone can convert, whatever their income. The limits on direct Roth contributions don't apply.
• No undo. Since 2018 a conversion can no longer be recharacterized back into a traditional IRA. Once done, the tax is owed.
• Pay the tax from outside money if possible. Using part of the converted amount to pay the tax shrinks what gets the Roth benefit and, under 59½, that withheld part can owe the 10% additional tax.
• Timing matters. Conversions tend to make the most sense in low-income years: a gap between jobs, early retirement before Social Security and RMDs begin, or a year with unusual deductions. Spreading conversions over several years can keep each year's income within a lower bracket.

The backdoor Roth and the pro-rata rule

High earners above the Roth income limit sometimes make a nondeductible traditional IRA contribution and then convert it, a two-step move nicknamed the "backdoor Roth." It is legal, but the pro-rata rule often makes it more taxable than people expect. When you convert, the IRS treats the conversion as coming proportionally from all of your traditional, SEP and SIMPLE IRA balances combined, not just the account you choose.

Pitfalls that cost people money

• Contributing to a Roth above the income limit. An ineligible contribution is an excess contribution, taxed at 6% for each year it stays. It can be withdrawn (with its earnings) or recharacterized as a traditional contribution before the filing deadline.
• Forgetting Form 8606. Without a record of nondeductible contributions, after-tax money can end up taxed again when it comes out.
• Comparing only today's rate with today's brackets. The decision is about your rate at withdrawal, which depends on all of your future income, including RMDs from any traditional balances.
• Treating "deductible" as "worth more." At equal rates the deduction is exactly offset by the later tax. It is worth more only if your later rate is lower.

Roth versus traditional IRA at a glance

How Finabase helps

Finabase is a research tool; it doesn't hold IRAs, calculate your taxes or know your bracket. It is useful for the investment side of the decision. A portfolio can mirror what you hold in each account, with cost, gains and dividends for every position, which makes it easier to see how much sits in pre-tax versus Roth money if you keep one portfolio per account. The comparison page puts candidate funds on one rebased chart, and each fund's symbol page has its quote, profile and dividend history. The Retirement accounts explained: 401(k), IRA, Roth and 2026 limits guide covers the account types, limits and withdrawal rules that sit around this choice, and Compound interest: how growth on growth builds wealth explains why the same rate gap matters more the longer the money grows.

Frequently asked questions

Is a Roth or a traditional IRA better?

Neither is better in general. At the same tax rate now and in retirement they produce the same after-tax result; a traditional IRA wins if your rate will be lower when you withdraw, and a Roth wins if it will be higher. Many people hold both to hedge the uncertainty.

Can I contribute to both in the same year?

Yes, as long as your combined contributions stay within the 2026 limit of $7,500 ($8,600 at 50 or older) and you meet the Roth income test for the Roth part.

What if my income is too high for a Roth IRA?

You can still contribute to a traditional IRA, deductible or not, and you can convert traditional IRA money to a Roth at any income. If you hold other pre-tax IRA balances, the pro-rata rule makes part of any conversion taxable.

When can I take money out of a Roth IRA without tax?

Your own contributions can come out any time without tax or penalty. Earnings are tax-free once the account has passed the five-year period and you are 59½ or older, disabled, using up to $10,000 for a first home, or a beneficiary.

Do I pay tax when I convert to a Roth?

Yes. The pre-tax amount you convert is ordinary income in the year of the conversion and is taxed at your marginal rates. The conversion itself isn't subject to the 10% additional tax, but withdrawing converted money within five years before 59½ can be.

Summary

The Roth-versus-traditional choice is a question about tax rates, not about investments. Paying tax before growth or after growth gives the same result when the rate is the same, so the decision hinges on whether your rate will be higher or lower when the money comes out, plus secondary factors such as RMDs, flexibility, AGI-based benefits and state taxes. For 2026, Roth contributions phase out at $153,000–$168,000 (single) and $242,000–$252,000 (joint), and the traditional deduction phases out at lower incomes if you have a workplace plan. Roth withdrawals follow a fixed order, with five-year clocks for the account and for each conversion. Conversions are open to everyone, cost income tax in the year they happen, and are permanent.