401(k) vs. 403(b): What's the Real Difference?

A 401(k) and a 403(b) are both employer-sponsored retirement accounts that let you invest pre-tax or Roth dollars straight from your paycheck, often with an employer match on top. For the employee sitting down to enroll, they feel almost identical. The real difference comes down to who's legally allowed to offer each one, and a handful of rules that follow from that.

What's Identical

Both let you contribute directly from payroll, pre-tax or as Roth (after-tax), depending on your employer's specific plan.
Both share the same annual contribution limits, set and updated by the IRS each year, regardless of which plan you're in.
Both often include an employer match, though the exact match formula varies by employer, not by plan type.
Both grow tax-deferred (or tax-free for Roth) until retirement withdrawals begin.

Where They Actually Differ

Investment Menu

401(k)s typically offer broader mutual fund/ETF selection; older 403(b)s have leaned on annuities

Fees

Older or smaller 403(b) plans have historically carried higher admin fees, worth checking your disclosure

Extra Catch-Up

Some 403(b)s offer a 15-years-of-service catch-up, unavailable in 401(k) plans

A Practical Example

Take two people earning identical salaries: one works as a software engineer at a private tech company, the other as a public school teacher. Both contribute 8% of their paycheck and get a 4% employer match. Mechanically, their accounts behave the same way, same contribution limits, same tax treatment, same growth potential. The teacher's 403(b), though, may have a narrower list of fund choices than the engineer's 401(k), and it's worth that teacher specifically checking whether their plan charges higher administrative fees, since 403(b) fee structures have historically varied more widely between providers.

Nondiscrimination Testing: A Technical but Real Difference

401(k) plans must pass IRS nondiscrimination tests each year, ensuring the plan doesn't disproportionately benefit highly paid employees over rank-and-file staff. Many 403(b) plans, particularly at government agencies and church-affiliated organizations, are exempt from this testing entirely. In practice, this rarely affects an individual employee's day-to-day experience, but it's part of why the two plan types exist as separate categories under the tax code rather than being merged into one.

Which One Do You Have?

Check your specific plan's fund lineup and fee disclosure, they matter more day-to-day than the account's name.

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Frequently Asked Questions

Which one is better, a 401(k) or a 403(b)?

Neither is inherently better. You typically don't get to choose, your employer type determines which one you're offered. What matters more is your specific plan's investment options, fees, and whether there's an employer match.

Can I have both a 401(k) and a 403(b)?

Yes, if you work for two different employers, or switch jobs during the year, you could contribute to both, though the combined employee contribution limit across both plans generally still applies.

What happens to my 403(b) if I leave a nonprofit for a private company?

You can typically roll it over into your new employer's 401(k) or into an IRA, similar to how a standard 401(k) rollover works when changing jobs between two for-profit employers.

Are 403(b) fees always higher than 401(k) fees?

Not always, but historically this has been a more common issue with 403(b) plans, especially older ones built around annuity products. It's always worth checking your specific plan's fee disclosure rather than assuming based on plan type.