Roth vs Traditional: How to Decide When You Pay the Tax
Updated: Oct 2
Key points
Traditional vs Roth comes down to one question: pay tax on this money now, or later.
If your tax rate is the same now and when you withdraw, the two come out equal. The difference comes from the rate changing.
A traditional contribution usually saves tax at your top rate today. In retirement, withdrawals are taxed across all brackets, which can lower the average rate, unless other income fills the low brackets first.
In a 401(k), anyone whose plan offers Roth can choose it. In an IRA, your income and workplace plan coverage decide which options you have.
Splitting between the two is a reasonable answer, and you can revisit it every year.
Whether it's your 401(k) or an IRA, you'll run into the same choice: traditional (pre-tax) or Roth. The labels differ a bit by account, and the rules around them differ a lot. But the question underneath is always the same. Do you want to pay tax on this money now, or later?
There's no right answer for everyone. Let's look at the concept and the math first, then apply it to your 401(k) and to an IRA.
Roth vs Traditional: The Core Idea
Traditional (pre-tax). You get a tax break now. The money grows tax-deferred, and everything, contributions and growth, is taxed as ordinary income when you withdraw it in retirement.
Roth. No tax break now. You contribute money you've already paid tax on. It grows tax-free, and qualified withdrawals in retirement are tax-free. Qualified generally means you're 59½ or older and the account has met a five-year rule (IRS).
The math
The decision comes down to your tax rate now compared with your tax rate when you withdraw. Here's an example with $1,000 of pay, a 24% tax rate (IRS) today, and investments that grow five times over.
Traditional: the full $1,000 goes in and grows to $5,000. At withdrawal it's taxed at 24%, leaving $3,800.
Roth: you pay $240 in tax first, so $760 goes in and grows to $3,800. At withdrawal, no tax. You keep $3,800.
Same result. When your tax rate is the same now and later, the two are equal. The difference only shows up when the rates differ:
Tax rate at withdrawal | Traditional keeps | Roth keeps |
12% (lower than today) | $4,400 | $3,800 |
24% (same as today) | $3,800 | $3,800 |
32% (higher than today) | $3,400 | $3,800 |
Illustrative example. The 12%, 24%, and 32% rates are 2026 federal tax brackets (IRS).
So the real question is where your tax rate will be when the money comes out of the account.
Why the rate at withdrawal is often lower than it looks
If your income in retirement were the same as today, the total tax on it would be the same too. The difference is which dollars the traditional contribution touches.
Today, a traditional contribution comes off the top of your income, so it saves tax at your highest rate, your marginal rate. In retirement, if traditional withdrawals are your main income, they're taxed like any other income: the first dollars are covered by the standard deduction, the next ones fall into the 10% and 12% brackets, and only the last ones reach your top rate.
Here's an example with the same income before and after retirement, using 2026 brackets for a single filer (IRS). Say you earn $150,000 today. After the $16,100 standard deduction, your top dollars are taxed at 24%, so each dollar you put into a traditional 401(k) saves 24 cents. In retirement, you withdraw the same $150,000 a year from traditional accounts and have no other income. The total tax is $24,734, the same as on $150,000 of pay today: the first $16,100 is untaxed, the next $12,400 is taxed at 10%, the next $38,000 at 12%, the next $55,300 at 22%, and only the last $28,200 at 24%. That's about 16.5% of what you withdrew. Money that saved 24% on the way in paid about 16.5% on the way out, on average. Put differently: if all your savings were in Roth, the standard deduction and the lowest brackets would go unused in retirement. The last dollars you withdraw are still taxed at 24%, the same rate you saved at. That's why the answer isn't all-or-nothing: traditional money that fills your lower brackets in retirement comes out lightly taxed, and beyond that point the two options even out.
The picture changes if other income fills the lower brackets first. Social Security, a pension, or rental income can use up the standard deduction and the 10% and 12% brackets, and then your withdrawals are taxed at higher rates. The more other types of income you expect in retirement, the smaller this advantage gets.
Why a maxed-out Roth holds more
Contribution limits are dollar amounts, and they're the same whether you choose traditional or Roth. But a dollar in a Roth is all yours, while a dollar in a traditional account still has tax owed on it. So if you're contributing the maximum, a Roth holds more after-tax money. Traditional savers can invest their tax savings, but that money goes into a taxable account, where dividends and gains are taxed along the way.
What points toward traditional
You're in a high bracket now. Peak earning years save the most per dollar deducted.
You expect lower income in retirement. Or several low-income years before Social Security and required withdrawals start, which is common in early retirement. Those years can be used to convert traditional money to Roth at low rates.
You plan to move. Leaving a high-tax state for a state with no income tax means you deduct at today's state rate and may pay no state tax later.
A lower income today helps you elsewhere. Traditional contributions lower your adjusted gross income. That can affect eligibility for direct Roth IRA contributions, a deductible traditional IRA, some tax credits, and income-driven student loan payments.
What points toward Roth
You're in a low bracket now. Early career, a career break, a year with partial income, or the first year after moving to the US. Paying tax at 10% or 12% (IRS) now can be a good trade.
You expect higher income later. A rising career, or a large traditional balance that will produce big required withdrawals.
You already have a lot of traditional money. Adding Roth gives you a choice later about which bucket to withdraw from each year. Some people call this tax diversification.
Required minimum distributions. Traditional accounts require withdrawals starting at 73, or 75 if you were born in 1960 or later (IRS, IRS regulations), whether you need the money or not. Roth IRAs and Roth 401(k)s have no required withdrawals during your lifetime (IRS).
What counts as income in retirement. Traditional withdrawals count as taxable income; qualified Roth withdrawals don't. That income affects more than your tax bill. It's used to set Medicare premiums, to decide how much of your Social Security is taxed, and to determine eligibility for income-based programs, including health insurance subsidies. You don't need to know today which of these will apply to you. Roth money gives you income in retirement that doesn't count toward any of them.
Your spouse or your heirs. If one spouse dies, the survivor usually files as single, with narrower tax brackets, on similar withdrawals. And heirs who inherit traditional money pay income tax on it; Roth money passes to them free of income tax, though most heirs other than a spouse must empty an inherited account within 10 years (IRS).
Future tax law is the one thing nobody knows. Rates could rise or fall. That uncertainty is one reason some people split their contributions rather than rely on one outcome.
Applying It to Your 401(k)
In a 401(k), you usually choose how each paycheck contribution goes in: traditional, Roth, or a mix.
One shared limit. $24,500 combined in 2026, or $32,500 if you're 50 or older ($35,750 at ages 60–63) (IRS). Every dollar you put in as Roth is a dollar you can't put in as traditional.
No income limits. Anyone whose plan offers a Roth option can use it, at any income (IRS).
You decide paycheck by paycheck. Most plans let you change your split at any time, and the change applies to future paychecks. So for this year, what matters is how your remaining paychecks are set up before the last payroll of the year. What's already contributed stays as it went in: Roth contributions can't be switched to pre-tax later (IRS).
Employer match. Matches have traditionally gone in as traditional money, even when your own contributions are Roth. Since SECURE 2.0, some plans let you choose Roth for the match. If you do, the match has to be fully vested, and it's taxable income in the year it's made, reported on Form 1099-R rather than withheld from your paycheck (IRS).
Catch-up contributions for higher earners. Starting in 2026, if you're 50 or older and earned more than $150,000 in FICA wages from that employer the previous year, your catch-up contributions must go in as Roth (IRS).
Your plan's options. Not every plan offers a Roth option. If yours doesn't, the question is settled for now.
Applying It to Your IRA
The concept is the same in an IRA (Individual Retirement Account). What's different is that your income and your workplace plan decide which options you actually have.
One shared limit. $7,500 across all your IRAs in 2026, or $8,600 if you're 50 or older (IRS). You can split it between traditional and Roth.
You can decide after the year ends. Contributions for a tax year can be made until the tax filing deadline, usually April 15 of the following year, when you already know your income. Filing extensions don't extend it (IRS).
Who can deduct a traditional IRA
Anyone with earned income can contribute to a traditional IRA. Whether the contribution is tax-deductible depends on workplace plan coverage and income.
The table is read from the point of view of the person contributing. For 2026:
Your situation | Full deduction | Phase-out | No deduction |
You have no workplace plan, and neither does your spouse (if married) | Any income | — | — |
You're covered by a workplace plan, single or head of household | Under $81,000 | $81,000–$91,000 | $91,000+ |
You're covered by a workplace plan, married filing jointly | Under $129,000 | $129,000–$149,000 | $149,000+ |
You're not covered, but your spouse is, married filing jointly | Under $242,000 | $242,000–$252,000 | $252,000+ |
Each spouse checks their own row. If only one of you has a workplace plan, both of you can still contribute: the covered spouse's deduction phases out at $129,000–$149,000, and the other spouse's at $242,000–$252,000, both based on your joint income (IRS). The table covers single, head of household, and married filing jointly. For married filing separately with a workplace plan, the range is $0–$10,000 (IRS).
Who can contribute to a Roth IRA directly
Direct Roth IRA contributions phase out at $153,000–$168,000 for single filers and $242,000–$252,000 for married couples filing jointly, and $0–$10,000 for married filing separately (IRS). Workplace plan coverage doesn't matter here.
What that means in practice
Put the two limits together, and most people land in one of three situations:
Both options are open. Your income is under the limits, or you have no workplace plan. The concept above applies directly. A few IRA-specific points: Roth IRA contributions can come out anytime without tax or penalty (IRS); a Roth 401(k) is different, since early withdrawals there come out as a mix of contributions and earnings (IRS), and traditional IRAs have required withdrawals while Roth IRAs don't (IRS). And if you might do a backdoor Roth IRA in the future, traditional IRA balances can make it partly taxable.
Your income is too high to deduct, but under the Roth limit. A nondeductible traditional IRA gives little advantage on its own. The Roth IRA is the practical choice.
Your income is above the Roth limit. Direct Roth contributions aren't available. The route is the backdoor Roth IRA: a nondeductible traditional contribution, converted to Roth.
Because traditional 401(k) contributions lower your adjusted gross income, they can sometimes move you from one situation to another.
If you're married and one spouse doesn't work, the non-working spouse can still contribute to an IRA through a spousal IRA (IRS), as long as you file jointly and the working spouse has enough earned income. The same deduction and income rules apply.
How to Think About It
You don't need a perfect forecast of your tax rate 30 years from now. You need a reasonable view of where you are today compared with where you're likely to be.
Here's how I'd frame it:
Is this a high-income year for you, or a low one?
What does your income look like in retirement: pension, Social Security, rental income, large traditional balances?
Are there years ahead with unusually low income, like early retirement or a career break?
Do you plan to stay in your current state?
How much do you already have in traditional and in Roth?
For an IRA: which of the three situations above are you in?
If most answers point one way, that's a strong signal. If they're mixed, splitting is a reasonable answer. And the choice isn't permanent: you can change it every year as your situation changes.
Summary
Choosing between traditional and Roth is choosing when to pay tax. Traditional gives you a tax break now and taxes withdrawals later; Roth taxes the money now and lets it come out tax-free. If your rate is lower at withdrawal, traditional wins; if it's higher, Roth wins; if it's the same, they're equal. In a 401(k), the choice is open to anyone whose plan offers Roth. In an IRA, income limits and workplace plan coverage narrow the options. Most people can't forecast their future rate precisely, which is why splitting is a common answer.
FAQs
Is Roth or traditional better? Neither in general. It depends on your tax rate now compared with your rate when you withdraw, plus factors like other retirement income, required withdrawals, and heirs.
Can I split my 401(k) contributions between traditional and Roth? Yes, if your plan offers Roth. The combined limit is $24,500 in 2026, or $32,500 if you're 50 or older (IRS).
Does a Roth 401(k) lower my take-home pay more than traditional? Yes. The full contribution goes into the account either way, but Roth contributions don't reduce your taxable wages, so more tax is withheld from the rest of your paycheck (IRS). Payroll taxes (Social Security and Medicare) apply to 401(k) contributions either way.
Can I switch past Roth 401(k) contributions to traditional? No. You can change your split for future paychecks, but Roth contributions already made can't be changed to pre-tax (IRS).
Can I deduct a traditional IRA if I have a 401(k) at work? It depends on your income. For 2026, the deduction phases out at $81,000–$91,000 for single filers and $129,000–$149,000 for married couples filing jointly when the contributing spouse is covered (IRS).
What if my income is too high for a Roth IRA? Direct contributions phase out at $153,000–$168,000 for single filers and $242,000–$252,000 for married couples filing jointly in 2026 (IRS). Above that, the route is a backdoor Roth IRA.
Transparency Note: I'm the human behind the keyboard — the ideas, stories, and decisions here are mine. I collaborate with AI throughout the writing process: brainstorming, drafting, smoothing out grammar and flow, assisting with research, and creating the visuals you see throughout my posts.
Disclaimer: The information provided in this blog post is for educational and informational purposes only. I am an AFC® (Accredited Financial Counselor) Candidate, not a Certified Financial Planner (CFP), Certified Public Accountant (CPA), tax advisor, attorney, or Investment Adviser Representative (IAR). The content herein is not intended to be a substitute for investment, tax, or legal advice from a licensed professional. Always seek the advice of a qualified professional with any questions you may have regarding your individual financial situation. The opinions expressed are my own and do not represent the views of my current or former employer.
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