What Is the Difference Between 401(a) and 403(b)?

The main difference between a 401(a) and a 403(b) is who controls the money going in. A 401(a) plan is employer-controlled: the employer decides whether you contribute, how much, and what it will add. A 403(b) is employee-directed: you choose how much to defer from your paycheck, up to the annual limit. Both are used by public-sector and nonprofit workers, both share the same $72,000 combined contribution ceiling for 2026, and both offer similar tax treatment, but they diverge on contribution control, investment choices, vesting, and the catch-up options available near retirement.¹

Which Employers Offer Which Plan

A 401(a) is a qualified retirement plan typically offered by governmental entities: state agencies, municipalities, and public universities. Some nonprofits sponsor 401(a) plans too, but that is less common. The “401(a)” label refers to the broad section of the tax code governing qualified employer trusts, and the familiar 401(k) is technically a subtype of 401(a) with a cash-or-deferred arrangement attached.²

A 403(b) is restricted to public schools, colleges and universities, churches, and organizations with tax-exempt status under Section 501(c)(3). Cooperative hospital service organizations and certain ministers also qualify.³ If your employer isn’t on that list, it cannot offer a 403(b).⁴

Many public employers run both plans side by side. A state university might enroll you in a mandatory 401(a) and also give you access to a voluntary 403(b) for additional savings.⁵

Who Decides What Gets Contributed

In a 401(a) plan, the employer designs the contribution structure. The employer decides whether you must contribute, how much, and what it will put in on top. Many governmental 401(a) plans require employees to contribute a fixed percentage of pay, with the employer adding a set match or flat amount. You generally cannot change your contribution rate or opt out.

A 403(b) works the opposite way. You decide whether to participate and how much to defer from your salary, up to the annual limit. The employer may offer a match or make additional contributions, but the employee drives the savings decision. That voluntary, employee-directed structure is what makes a 403(b) feel much like a private-sector 401(k) in day-to-day use.

Contribution Limits for 2026

The annual limit on elective salary deferrals under Section 402(g) is $24,500 for 2026. This cap applies to the deferrals you voluntarily direct into a 403(b) and to 401(k) plans. It does not apply to the mandatory “picked-up” contributions in a standalone 401(a) that lacks a cash-or-deferred feature.⁶ The $24,500 is a per-person figure across all eligible plans, not per plan. If you defer into a 403(b) and a 401(k) in the same year, your combined elective deferrals cannot exceed that one cap.⁷

The total annual addition limit under Section 415(c), which combines employee deferrals, employer matching, and employer nonelective contributions, is $72,000 for 2026, or 100% of compensation, whichever is less. That ceiling applies identically to both plan types.¹⁸

Starting in 2024, employers sponsoring either plan can also provide matching contributions when employees make qualifying student loan payments, even when the employee isn’t deferring salary. Those matches count against the same $72,000 annual addition limit.⁹

Catch-Up Contributions

Both plans let participants aged 50 and older make catch-up contributions above the standard limit. For 2026, the general catch-up is $8,000.⁷

Super Catch-Up for Ages 60 Through 63

Under the SECURE 2.0 Act, participants who are 60, 61, 62, or 63 during 2026 can contribute up to $11,250 in catch-up contributions instead of the standard $8,000. That higher limit applies to 401(a) plans with a 401(k) feature and to 403(b) plans.¹

The 403(b) 15-Year Service Catch-Up

The 403(b) has a catch-up provision no 401(a) can offer. If you have worked at least 15 years for the same qualifying employer, such as a public school system, hospital, or church, you can contribute extra on top of the age-based catch-up.¹⁰

The extra annual amount is the lowest of three calculations:

$3,000
$15,000 minus the total 15-year catch-up amounts you’ve used in prior years
$5,000 multiplied by your years of service with the employer, minus all elective deferrals you’ve ever made to that employer’s plans

The lifetime cap is $15,000 per employer. Once you’ve used it up, that catch-up is gone, though the age-based catch-up remains available separately.¹¹

Upcoming Roth Requirement for High Earners

Beginning in 2027, catch-up contributions for employees who earned more than $150,000 in the prior year must be designated as Roth (after-tax) contributions. The rule applies to 401(k), 403(b), and governmental 457(b) plans. For 2026, it is not yet in effect, but plan sponsors are already preparing for the transition.¹²

Investment Choices

A 401(a) plan holds assets in a formal trust, which gives sponsors broad flexibility in picking investments. Depending on the plan, options may include individual stocks, bonds, index funds, and target-date funds, much like a 401(k).²

A 403(b) is limited by statute to two funding vehicles: annuity contracts from an insurance company, or custodial accounts invested exclusively in mutual funds. Church plans may also use retirement income accounts. This restriction often means 403(b) participants face a narrower menu than 401(a) participants, especially when the plan leans heavily on annuity products with embedded fees that can be hard to compare.⁴

Vesting Schedules

Vesting controls when you actually own the employer’s contributions. Your own contributions, whether mandatory in a 401(a) or voluntary in a 403(b), are always immediately vested. The difference shows up on the employer side.

Governmental 401(a) plans can impose lengthy vesting periods on employer contributions, sometimes requiring 10 to 20 years of service before you fully own the employer’s share. Leave before vesting and you forfeit some or all of those contributions. A 403(b) employer match can also carry a vesting schedule, but these tend to be shorter, and many 403(b) plans vest employer contributions immediately. If you’re weighing a job offer that includes a 401(a), the vesting schedule is one of the first details to check.

Moving Money Between the Two

Funds from a 401(a) can be rolled into a 403(b), a traditional IRA, another 401(a), or a 401(k), and the reverse is equally true. The IRS rollover chart treats 401(a) plans as qualified plans alongside 401(k) and profit-sharing plans, and all of these accept pre-tax rollovers from 403(b) plans.¹³ If you move between a government job with a 401(a) and a nonprofit job with a 403(b), your accumulated savings can follow you without a tax bill, provided the rollover is done properly.

One caution for public safety employees. Police officers, firefighters, EMTs, corrections officers, and other qualified public safety workers in a governmental plan can avoid the 10% early withdrawal penalty when they separate from service after age 50 or after 25 years of service, whichever comes first. That exception applies to governmental 401(a) and other governmental defined contribution plans, but it does not survive a rollover into an IRA.¹⁴ Keep the money in the employer plan if you expect to need early access.

The Differences at a Glance

Sponsoring employers: 401(a) plans are offered mainly by governmental entities and some nonprofits; 403(b) plans are limited to public schools, 501(c)(3) organizations, and churches.
Contribution control: in a 401(a), the employer sets the structure and employee contributions are often mandatory; in a 403(b), the employee chooses how much to defer.
2026 elective deferral limit: $24,500 under Section 402(g), applying to 403(b) salary deferrals and to 401(k) plans. A standalone 401(a) without a 401(k) feature uses mandatory contributions not governed by 402(g).
2026 total contribution limit: $72,000 (or 100% of compensation) under Section 415(c), applying to both plan types.
Catch-ups: both allow $8,000 at age 50 and over, and $11,250 for ages 60 through 63. Only the 403(b) offers the additional 15-year service catch-up.
Investments: 401(a) trusts can hold a broad range of investments; 403(b) plans are limited to annuity contracts and mutual fund custodial accounts.
Vesting: governmental 401(a) plans may require years of service before employer contributions fully vest; employee deferrals in a 403(b) are always immediately vested.
Rollovers: funds move freely between 401(a), 403(b), 401(k), and traditional IRA accounts.

For most public-sector and nonprofit employees, the choice between these plans isn’t really a choice. Your employer picks which plan to offer, and often offers both. Knowing where they diverge tells you what to prioritize: check the vesting schedule on any 401(a), maximize your elective deferrals in a 403(b), and if you’ve spent 15 or more years at the same qualifying employer, ask whether your 403(b) plan document allows the service-based catch-up before that savings room goes unused.

1
Internal Revenue Service. COLA Increases for Dollar Limitations on Benefits and Contributions
2
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3
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