If you have ever tried to figure out the best way to save for retirement, you have probably come across two heavyweights: the 401(k) and the Roth IRA. Both are great tools. Both come with tax benefits. But they work in completely different ways, and picking the right one — or the right combination — can make a big difference to how much money you have when you finally stop working.
Let us break down how each one works, compare them side by side, and help you figure out which one makes the most sense for your situation.
How a 401(k) Works
A 401(k) is a retirement savings plan offered by your employer. When you sign up, a portion of each paycheck goes straight into your 401(k) account before taxes are taken out. That is the key feature — the money goes in pre-tax.
Here is what that means in practice. Say you earn $60,000 a year and contribute $6,000 to your traditional 401(k). Your taxable income drops to $54,000. You pay less income tax right now, which means your paycheck is bigger than it would be if you saved the same amount in a regular brokerage account.
The trade-off? When you withdraw the money in retirement, you will pay income tax on it then. Every dollar you take out gets taxed at your ordinary income tax rate — whatever that happens to be at the time.
For 2025, you can contribute up to $23,500 to your 401(k). If you are 50 or older, you can add an extra $7,500 in catch-up contributions. And if you are between 60 and 63, there is a new super catch-up provision that lets you contribute an additional $11,250.
Many employers also offer a matching contribution — they will match a percentage of what you put in, up to a certain limit. This is essentially free money, and you should always try to contribute at least enough to get the full match. Use our 401(k) calculator to see how your contributions and employer match add up over time.
How a Roth IRA Works
A Roth IRA flips the tax benefit around. Instead of getting a tax break now, you pay taxes on the money going in — but then everything comes out completely tax-free in retirement. Contributions, growth, dividends, all of it. Tax-free.
That is a really powerful benefit if you think your tax rate will be higher in the future than it is today. And for younger workers, that is often a pretty safe bet — most people earn more later in their careers than they do at the start.
For 2025, the maximum you can contribute to a Roth IRA is $7,000 ($8,000 if you are 50 or older). That is significantly less than the 401(k) limit, but the tax-free growth makes it extremely valuable over decades of compounding.
There is one catch: income limits. If you are single and your modified adjusted gross income (MAGI) is over $150,000 in 2025, the amount you can contribute starts to phase out. Above $165,000, you cannot contribute directly to a Roth IRA at all. For married couples filing jointly, the phaseout range is $236,000 to $246,000.
Side-by-Side Comparison
Let us put these two accounts next to each other so you can see the differences at a glance:
- Tax treatment of contributions: 401(k) = pre-tax (reduces your taxable income now). Roth IRA = after-tax (no tax break today).
- Tax treatment of withdrawals: 401(k) = taxed as ordinary income. Roth IRA = completely tax-free.
- 2025 contribution limit: 401(k) = $23,500. Roth IRA = $7,000.
- Employer match: 401(k) = yes (if your employer offers one). Roth IRA = no.
- Income limits: 401(k) = none. Roth IRA = yes (phaseout for higher earners).
- Required minimum distributions (RMDs): 401(k) = yes (starting at age 73). Roth IRA = no.
- Early withdrawal penalty: Both charge 10% if you withdraw before age 59½, with some exceptions. Roth IRA contributions (but not earnings) can be withdrawn penalty-free at any time.
So Which One Should You Choose?
The honest answer is: it depends on your situation. But here are some general guidelines that work for most people.
A 401(k) tends to be better if:
- Your employer offers a match — always take the free money first
- You are in a high tax bracket right now and want to lower your current tax bill
- You want to save more than $7,000 per year in a tax-advantaged account
- You earn too much to qualify for a Roth IRA
A Roth IRA tends to be better if:
- You are early in your career and in a lower tax bracket
- You expect your income (and tax rate) to be higher in retirement
- You want tax-free income in retirement for more flexibility
- You do not want to deal with RMDs — Roth IRAs have none
Why Not Both?
Here is the thing a lot of people do not realize: you do not have to choose one or the other. You can contribute to both a 401(k) and a Roth IRA in the same year, as long as you stay within each account's contribution limits.
A popular strategy is to contribute enough to your 401(k) to get the full employer match, then max out your Roth IRA, and then go back to your 401(k) if you have money left to save. This gives you a mix of pre-tax and tax-free money in retirement, which provides flexibility when it comes to managing your tax bill later.
To see how different contribution strategies affect your paycheck, try our salary calculator — you can adjust your 401(k) contribution percentage and see the impact on your take-home pay in real time.
What About a Roth 401(k)?
Many employers now offer a Roth 401(k) option alongside the traditional 401(k). This combines features of both: you get the higher contribution limit of a 401(k) ($23,500) with the after-tax contributions and tax-free withdrawals of a Roth.
If your employer offers this option and you like the idea of tax-free retirement income but want to save more than the $7,000 Roth IRA limit allows, a Roth 401(k) can be a great choice. Starting in 2024, Roth 401(k)s no longer require RMDs either, making them even more similar to Roth IRAs.
A Quick Note on the Backdoor Roth
If you earn too much to contribute directly to a Roth IRA, you might have heard of the "backdoor Roth" strategy. This involves making a non-deductible contribution to a traditional IRA and then converting it to a Roth IRA. It is legal and widely used, though it comes with some tax complications if you already have money in a traditional IRA (look up the "pro-rata rule" if this applies to you).
The Bottom Line
Both 401(k)s and Roth IRAs are excellent retirement savings tools. The best choice depends on your current income, your expected future income, and whether your employer offers a match. For many people, using both is the smartest play.
The most important thing is to start saving — and to save as much as you comfortably can. Compound growth over decades is incredibly powerful, and every year you wait is a year of growth you miss out on.
Run your numbers through our 401(k) calculator and see how your contributions translate into retirement savings. Even a small increase in what you save each month can make a massive difference over 20 or 30 years.