401(k) vs IRA vs Roth: Which Retirement Account Is Best?

If you're trying to figure out where to save for retirement, the alphabet soup of account types—401(k), Traditional IRA, Roth IRA, Roth 401(k), SEP IRA, SIMPLE IRA—can feel like a maze. The good news is that for most people, the decision comes down to three core accounts: the 401(k) (or equivalent employer plan), the Traditional IRA, and the Roth IRA. Each has different rules, limits, and tax treatments, and the order in which you fund them matters more than most people realize.

This guide breaks down each account, explains the 2024 contribution limits and tax treatment, walks through income phase-outs, and gives you a clear priority order for funding them. We'll also cover employer matches, early withdrawal rules, and Required Minimum Distributions. To model your own scenario, our Retirement Calculator can project outcomes based on your contributions.

The three core accounts, defined

401(k): the employer-sponsored workhorse

A 401(k) is a retirement plan offered by your employer. You contribute pre-tax dollars from your paycheck, the money grows tax-deferred, and you pay ordinary income tax on withdrawals in retirement. Many employers offer a match—typically 50 cents to a dollar on the first 3–6% of your salary—which is the closest thing to free money in personal finance.

The 2024 employee contribution limit is $23,000 ($30,500 if you're 50 or older, thanks to a $7,500 catch-up). Combined employer + employee contributions can reach $69,000 ($76,500 with catch-up). If your employer offers a Roth 401(k) option, you can split contributions between traditional (pre-tax) and Roth (after-tax) within the same plan.

Traditional IRA: the individual pre-tax account

A Traditional IRA is an individual retirement account you open at a brokerage (Fidelity, Vanguard, Schwab, etc.). You contribute pre-tax money (if eligible), it grows tax-deferred, and withdrawals in retirement are taxed as ordinary income. The 2024 contribution limit is $7,000 ($8,000 if 50+).

The catch: deductibility of contributions depends on income and whether you (or your spouse) have a workplace retirement plan. Single filers covered by a workplace plan lose the deduction between $77,000 and $87,000 of modified AGI in 2024. If you're not covered by a workplace plan, the deduction is full regardless of income—unless your spouse is covered, in which case phase-outs apply.

Roth IRA: the after-tax, tax-free-growth account

A Roth IRA flips the tax treatment. You contribute after-tax dollars—no upfront deduction—but the money grows tax-free and qualified withdrawals in retirement are completely tax-free. The 2024 contribution limit is $7,000 ($8,000 if 50+), shared with any Traditional IRA contributions.

The catch: high earners can't contribute directly. In 2024, the Roth IRA contribution phases out for single filers between $146,000 and $161,000 of modified AGI, and for married couples filing jointly between $230,000 and $240,000. Above those limits, you need the "backdoor Roth" strategy (covered below).

Tax treatment comparison table

The priority order: where to put your next dollar

Most people can't max out every account, so the order matters. A sensible default for 2024:

1. 401(k) up to the employer match. If your employer matches 100% of contributions up to 5% of salary, contribute 5%. A 100% match is an immediate 100% return—nothing else comes close.
2. Pay off high-interest debt. Credit cards at 22% beat any retirement account. Clear these before going further.
3. Full emergency fund. Three to six months of expenses in cash. See our emergency fund guide for the framework.
4. Max HSA if eligible. A Health Savings Account is triple-tax-advantaged: pre-tax contributions, tax-free growth, tax-free withdrawals for qualified medical expenses. It's the only account with all three benefits.
5. Max Roth IRA. Tax-free growth and withdrawal flexibility (you can pull contributions any time) make this more attractive than a non-deductible Traditional IRA for most people.
6. Go back and max the 401(k). Once the Roth is full, return to the 401(k) up to the $23,000 limit.
7. Taxable brokerage. After all tax-advantaged accounts are maxed, invest in a standard brokerage account.

This order isn't universal. If you expect to be in a much lower tax bracket in retirement than you are now, traditional pre-tax contributions become more valuable than Roth. If you expect higher future rates—due to career trajectory or expected tax law changes—Roth becomes more attractive.

The employer match: do not leave this on the table

The most common 401(k) match formulas:

• Dollar-for-dollar up to 3–6% of salary. The most generous common match. A $100,000 earner with a 5% dollar-for-dollar match gets $5,000 of free money by contributing $5,000.
• 50 cents on the dollar up to 6%. Worth 3% of salary if you contribute the full 6%.
• Safe harbor nonelective 3%. Employer contributes 3% of your salary regardless of what you contribute.
• Profit-sharing discretionary match. Varies by year and company performance.

According to Vanguard's How America Saves report, about 40% of participants in plans with a match don't contribute enough to get the full match—leaving an average of $1,440 of free money on the table annually. If you take one thing from this guide, it's this: contribute at least enough to get the full employer match, even if you have credit card debt.

Income limits and the backdoor Roth

If your income exceeds the Roth IRA phase-out ($161,000 single, $240,000 MFJ in 2024), you can't contribute directly. But there's a legal workaround:

1. Contribute $7,000 to a non-deductible Traditional IRA. (Anyone with earned income can do this regardless of income.)
2. Convert the Traditional IRA to a Roth IRA. There's no income limit on conversions.
3. Since you contributed after-tax (non-deductible) dollars, only the earnings are taxable at conversion—usually near zero if you convert quickly.

Watch the pro-rata rule. If you have other pre-tax money in any Traditional IRA (including a SEP or SIMPLE IRA), the IRS requires you to prorate the conversion across all your IRA balances. This can trigger a large tax bill and undermine the strategy. The cleanest backdoor Roth setup is: no other Traditional IRA balances, or roll those balances into your 401(k) first.

Early withdrawal rules: where each account shines

One of the Roth IRA's underrated advantages is withdrawal flexibility. You can withdraw your contributions (not earnings) at any time, for any reason, with no tax and no penalty. This makes the Roth IRA a dual-purpose account—it can serve as a backup emergency fund or a college savings vehicle without the restrictions of a 529.

Traditional 401(k) and IRA withdrawals before age 59½ generally trigger a 10% penalty plus income tax. Exceptions include:

• Substantially equal periodic payments (Rule 72(t))
• First-time home purchase (up to $10,000 from an IRA)
• Qualified higher education expenses (IRA only)
• Birth or adoption distribution (up to $5,000, penalty-free)
• Medical expenses exceeding 7.5% of AGI
• Health insurance premiums while unemployed (IRA only)

For 401(k)s specifically, the "Rule of 55" allows penalty-free withdrawals from your current employer's plan if you leave your job at age 55 or later. This can be a useful bridge to age 59½ for early retirees.

Required Minimum Distributions (RMDs)

The SECURE Act of 2019 and SECURE 2.0 of 2022 raised the RMD starting age to 73 (rising to 75 in 2033). RMDs apply to:

• Traditional 401(k) balances
• Traditional IRA balances
• SEP and SIMPLE IRAs

Roth IRAs have no RMDs during your lifetime—you can leave the money growing tax-free indefinitely. Roth 401(k)s do have RMDs, but you can roll them into a Roth IRA to escape that requirement.

Failure to take an RMD triggers a 25% excise tax on the under-withdrawn amount (reduced from 50% by SECURE 2.0; further reduced to 10% if corrected timely). The first RMD can be delayed to April 1 of the year after you turn 73, but you'll then need to take two RMDs that year.

Tax diversification: why most people should have all three

Most retirement advice pushes you to optimize for current taxes. The smarter approach is to optimize for tax diversification—holding some pre-tax, some Roth, and some taxable money. Why? Because no one knows what tax rates will be in 10, 20, or 30 years, and your income in retirement won't be flat.

Tax diversification lets you control your taxable income in retirement year by year. In a year with large unexpected expenses, pull from Roth to keep taxable income low. In a low-income year, do Roth conversions. In a high-income year, pull from taxable accounts where long-term capital gains rates are favorable. This flexibility can save tens of thousands of dollars over a retirement.

A reasonable target allocation by the time you retire:

• 40–60% Traditional (pre-tax)—401(k), Traditional IRA
• 20–40% Roth—Roth IRA, Roth 401(k)
• 10–30% Taxable brokerage—long-term capital gains rates, step-up in basis at death

Roth vs Traditional: a decision framework

The single most consequential choice in retirement savings—more important than the specific funds you pick—is whether to save pre-tax (traditional) or after-tax (Roth). The wrong choice can cost you 10–20% of your lifetime tax bill. Here's a framework for deciding:

Choose Roth when:

• You're early in your career and likely in a lower bracket now than at peak earnings.
• You expect tax rates to rise generally (a reasonable bet given current federal debt levels).
• You want flexibility—Roth IRA contributions can be withdrawn penalty-free before retirement.
• You're a high earner but can use the backdoor Roth strategy to access tax-free growth.
• You expect a large taxable retirement income (pension, rental properties, large traditional balances) and want to diversify.

Choose Traditional when:

• You're in peak earning years (32%+ bracket) and expect to be in a lower bracket in retirement.
• You live in a high-tax state now but plan to retire in a no-tax state (Florida, Texas, Nevada, etc.).
• You're self-employed and the deduction materially reduces your current tax burden.
• You expect to do Roth conversions in low-income retirement years before RMDs begin.

Split the difference when:

Most people near retirement benefit from holding both pre-tax and Roth money. A 50/50 split gives you tax diversification: in retirement, you can pull from traditional up to the standard deduction and 10% bracket (very low tax), then pull from Roth for additional spending. This "tax bracket filling" strategy can save five figures per year in retirement taxes.

Common mistakes to avoid

Skipping the match. Not contributing enough to get the full employer match is the single most expensive mistake in retirement savings. It's literally leaving free money on the table.

Defaulting to the 401(k) target-date fund without checking fees. Target-date funds are convenient but often carry expense ratios of 0.50% or more. Over 30 years, that 0.50% drag can eat 10%+ of your final balance. Look for low-cost index funds inside the plan.

Withdrawing early for non-emergencies. The 10% penalty plus income tax can wipe out 30–40% of a withdrawal. Exhaust all other options—including Roth IRA contributions, which are penalty-free—before touching pre-tax balances.

Forgetting to name or update beneficiaries. Retirement accounts pass by beneficiary designation, not by your will. Stale beneficiaries (an ex-spouse, a deceased parent) cause massive legal headaches. Review beneficiaries after every major life event.

Treating the Roth IRA as a primary emergency fund. Yes, you can withdraw contributions penalty-free, but doing so permanently reduces your tax-advantaged retirement space. You can't "put back" contributions from prior years except in the current tax year before the filing deadline.

Not doing the backdoor Roth when your income qualifies. High earners who skip the backdoor Roth because it sounds complicated leave decades of tax-free growth on the table. Once set up, the process takes 15 minutes a year.

FAQ

Can I contribute to both a 401(k) and an IRA in the same year?

Yes. You can max out a 401(k) at $23,000 and an IRA at $7,000 simultaneously, for a total of $30,000 ($38,000 if 50+). IRA deductibility may be limited if you have a workplace plan, but Roth IRA contributions (if under the income limit) are unaffected by 401(k) participation.

What if I change jobs—what happens to my 401(k)?

You have four options: leave it with your former employer (if the balance is over $7,000), roll it into your new employer's 401(k) (if accepted), roll it into a Traditional IRA, or cash it out (don't—the penalty and tax are brutal). Rolling into an IRA typically gives you the widest investment selection and lowest fees.

Is Roth or Traditional better if I'm early in my career?

For most early-career savers, Roth wins. You're likely in a lower tax bracket now than you will be at peak career earnings, and decades of tax-free growth are enormously valuable. As your income climbs into the 32%+ brackets, traditional pre-tax contributions become more attractive.

What's the difference between a Roth IRA and a Roth 401(k)?

The Roth 401(k) follows 401(k) contribution limits ($23,000 in 2024) and has no income limits, but it's subject to RMDs (unless rolled to a Roth IRA). The Roth IRA has the much lower $7,000 limit and income phase-outs, but no RMDs and more flexible withdrawals.

Can I open an IRA if I'm self-employed?

Yes, and you have better options. A SEP IRA allows contributions up to 25% of compensation or $69,000 in 2024 (whichever is less). A Solo 401(k) allows employee + employer contributions up to $69,000. Both dwarf the standard IRA limit. Use our Retirement Calculator to model the impact of these higher limits.