403(b) Plans: How They Work and How They Differ from a 401(k)

Key Takeaways

A 403(b) is a tax-advantaged retirement plan restricted to a specific set of employers, public schools, 501(c)(3) tax-exempt organizations, and certain ministers, and its tax treatment closely mirrors the 401(k) most private-sector employees are familiar with. For how a 403(b) fits into a broader retirement savings strategy alongside IRAs, HSAs, and taxable accounts, see Swoopr's Investment Account Types hub and its Retirement Investing companion.

Direct answer: A 403(b) is an employer-sponsored retirement plan for employees of public schools and certain tax-exempt organizations. Like a 401(k), it allows pre-tax or Roth employee salary deferrals with tax-deferred or tax-free growth, and many plans add an employer match. Two things set it apart: some 403(b) plans, particularly older ones, still offer only insurance-company annuity contracts rather than a broad low-cost fund menu, a legacy of the plan's original design; and 403(b) elective deferrals are tracked under a separate IRS limit from 457(b) elective deferrals, so an employee with access to both plan types can generally contribute up to each plan's own limit rather than sharing one combined cap.

• 403(b) eligibility is employer-based: public schools, 501(c)(3) tax-exempt organizations, and certain ministers can sponsor a 403(b); most private-sector, for-profit employers cannot.
• Tax treatment mirrors a 401(k): pre-tax deferrals reduce current taxable income and are taxed on withdrawal; a Roth 403(b) option, where offered, takes after-tax deferrals with tax-free qualified withdrawals.
• 403(b) plan assets are held in one of three vehicles: an annuity contract, a custodial account invested in mutual funds, or, for church employees, a retirement income account.
• A unique 15-years-of-service catch-up contribution, set at fixed statutory dollar amounts, is available only in 403(b) plans, not in 401(k) or 457(b) plans.
• 403(b) and 457(b) elective deferral limits are tracked separately by the IRS, so employees with access to both can potentially defer into each up to its own limit in the same year.
• Current-year contribution limits, income thresholds, and catch-up amounts change annually; verify the exact figures for the year in question at IRS.gov before making contribution decisions.

What Is a 403(b) Plan?

A 403(b) plan, formally a "tax-sheltered annuity" plan under the origin of the name, is an employer-sponsored retirement plan restricted to a specific category of employer: public schools (kindergarten through 12th grade, colleges, and universities), tax-exempt organizations described under Internal Revenue Code Section 501(c)(3), and certain ministers. Employees at these organizations, teachers, professors, nurses, hospital staff, museum and nonprofit employees, and clergy, can typically participate. The plan gets its name from Section 403(b) of the Internal Revenue Code, the section that authorizes it, in the same way the 401(k) is named for the code section that authorizes it.

Functionally, a 403(b) works like a 401(k): the employee elects to defer a portion of salary into the plan, that money is invested inside the account, and the account grows without generating annual capital gains or dividend taxes along the way. The employer may add a matching contribution, a fixed non-elective contribution, or both, depending on the plan's design. Whether the employee's contribution reduces current taxable income (traditional, pre-tax) or is made after-tax with tax-free qualified withdrawals later (Roth, where the plan offers it) works the same way it does in a 401(k).

The Annuity-Menu Legacy: How a 403(b) Can Differ From a 401(k) in Practice

The IRS allows 403(b) plan assets to be held in one of three vehicles: an annuity contract purchased from an insurance company (a "403(b)(1)" arrangement), a custodial account invested in mutual funds (a "403(b)(7)" arrangement), or, for church employees, a retirement income account. A typical 401(k), by contrast, is built around a custodial trust holding a menu of mutual funds or exchange-traded funds chosen by the plan sponsor, with annuity options being the exception rather than the norm.

This is a real, historically significant structural difference, not just a technicality. Because the 403(b) originated as a tax-sheltered annuity vehicle, many older and smaller 403(b) plans, especially at K-12 school districts, have historically offered participants a menu dominated by insurance-company annuity products, often with higher expense ratios, surrender charges, and mortality-and-expense fees layered on top of the underlying investment cost, compared to a low-cost index fund menu. Some school-district 403(b) plans still operate this way today, sometimes through arrangements with multiple competing annuity vendors marketed directly to teachers.

The picture has shifted meaningfully over the past two decades. Many employers, particularly universities, hospitals, and larger nonprofits, now offer 403(b)(7) custodial accounts with a mutual fund lineup that looks very similar to a well-designed 401(k) menu, sometimes through the same recordkeepers that administer 401(k) plans for private employers. Whether a given 403(b) participant faces an annuity-heavy legacy menu or a modern low-cost fund lineup depends entirely on that employer's specific plan design, so this is a detail worth checking directly with your plan administrator or benefits office rather than assuming either extreme applies to your situation.

ERISA Status: Another Structural Difference

Most private-sector 401(k) plans are governed by the Employee Retirement Income Security Act (ERISA), which imposes fiduciary duties on the plan sponsor, disclosure requirements, and a claims process for participants. Public-school 403(b) plans are generally exempt from ERISA because ERISA does not apply to plans sponsored by government entities, and public schools are treated as government employers for this purpose. Many church-sponsored 403(b) plans are also exempt unless the church elects ERISA coverage. Non-governmental, non-church 403(b) plans sponsored by a 501(c)(3) organization can be subject to ERISA depending on the degree of employer involvement in the plan.

The practical effect is that ERISA's fiduciary protections and required disclosures, which apply to most 401(k) participants, may or may not apply to a given 403(b) participant depending on the sponsoring employer's type. This is one more reason the specifics of an individual 403(b) plan, its investment menu, fee structure, and governance, matter more than they would for a 401(k), where ERISA imposes a more consistent floor of protections across employers.

Contribution Mechanics

A 403(b) has two potential sources of money going in: the employee's own elective deferral from salary, and any contribution the employer chooses to make.

Employee elective deferrals

Employees elect what percentage or dollar amount of salary to defer into the plan, subject to the IRS's annual elective deferral limit, which is set and adjusted for inflation each year and shared conceptually with the 401(k) limit (both plan types use the same base annual deferral limit under the tax code, though as described below, the two are not aggregated with a 457(b)). Deferrals can generally be directed to a traditional pre-tax account, a Roth after-tax account where the plan offers one, or split between the two.

The age-50 catch-up

Employees aged 50 and older can generally make an additional catch-up contribution above the standard elective deferral limit, the same mechanism available in a 401(k).

The 15-years-of-service catch-up: unique to the 403(b)

A 403(b)-specific feature not available in a 401(k) or 457(b): an employee with at least 15 years of service with the same eligible employer, a public school, hospital, home health service agency, or church-related organization, can, if the plan permits it, defer an additional amount above both the standard limit and the age-50 catch-up. The increase is set by the IRS as the least of three fixed statutory figures: $3,000 for the year; a lifetime cap of $15,000 reduced by any 15-years-of-service catch-up already used in prior years; or $5,000 multiplied by years of service, reduced by elective deferrals made in earlier years. Unlike the standard annual deferral limit, these three figures are fixed by statute and are not adjusted for inflation each year. An employee who qualifies for both the 15-years-of-service catch-up and the age-50 catch-up can generally use both in the same year if the plan permits, since the two catch-up types are calculated independently.

Employer contributions

Employers can add a matching contribution, a non-elective (fixed) contribution, or both, on top of employee deferrals, subject to a separate, higher overall annual-additions limit that combines employee deferrals and employer contributions together. As with a 401(k) match, capturing a full available employer match is generally the highest-priority use of retirement savings dollars before directing money elsewhere, since it is an immediate, guaranteed return that no investment can reliably replicate.

All contribution limits, catch-up amounts (other than the fixed 15-years-of-service figures above), and income thresholds mentioned generically in this guide are adjusted by the IRS annually. Verify the current-year figures at IRS.gov before making a contribution decision.

The 403(b) + 457(b) Dual-Contribution Mechanic

Many public-sector and some nonprofit employees, most commonly public school and local-government employees, have access to both a 403(b) and a governmental 457(b) plan through the same employer. A common and reasonable assumption is that the two plans share one combined contribution limit, the way multiple 401(k) plans from unrelated employers in the same year generally do. That assumption is incorrect for the 403(b)/457(b) combination.

IRS guidance on 403(b) contribution limits specifically instructs employees to combine their 403(b) elective deferrals with deferrals to other plans they participate in, with an explicit carve-out for 457 plans. In practice, this means a 403(b) elective deferral limit and a 457(b) elective deferral limit are tracked under separate provisions of the tax code and are not required to be aggregated into a single combined ceiling the way, for example, deferrals to two unrelated employers' 401(k) plans in the same calendar year generally are.

For an employee with access to both plan types, the practical effect is the potential to defer money into each plan up to that plan's own separate limit in the same year, roughly doubling the total amount that can be tax-deferred compared with using only one of the two plans. This is a genuine, IRS-documented structural feature of how 403(b) and 457(b) plans are treated under the tax code, not a workaround or aggressive interpretation, though the exact current-year dollar limit for each plan changes annually and should be confirmed directly with your plan administrator and IRS guidance before relying on it for a specific contribution amount.

See Swoopr's companion guide to 457(b) plans for the same mechanic described from the 457(b) side, along with the governmental versus non-governmental distinction that materially affects a 457(b)'s risk profile.

Roth 403(b) and Required Minimum Distributions

Many 403(b) plans offer a Roth option alongside the traditional pre-tax deferral, letting participants choose after-tax contributions with tax-free qualified withdrawals later, the same structure as a Roth 401(k). Traditional (pre-tax) 403(b) balances are subject to required minimum distributions starting at the age set by the SECURE 2.0 Act, the same age that applies to traditional IRAs and 401(k)s. Roth 403(b) balances, like Roth 401(k) balances, were freed from RMD requirements during the original owner's lifetime effective January 1, 2024. For the full mechanics of how RMDs are calculated and the current age thresholds, see Swoopr's guide to Required Minimum Distributions.

A 403(b) can generally be rolled over into a traditional IRA, a Roth IRA (via a taxable conversion), or another employer's qualified plan when an employee leaves the sponsoring employer, similar to a 401(k) rollover. See Swoopr's guide to Rollover IRA Rules for the direct-versus-indirect rollover mechanics that apply.

Misconceptions vs. Reality

Common Mistakes

Never reviewing the actual investment menu. Because 403(b) plan quality varies so much by employer, from a low-cost mutual fund lineup to an annuity-heavy menu with layered insurance fees, defaulting into whatever option is presented first without comparing expense ratios and surrender terms across the available vendors can be costly over a multi-decade career.

Assuming a 403(b) and 457(b) share one contribution limit. Employees who have access to both plans sometimes underfund one or both because they assume, incorrectly, that maxing one plan uses up the other's limit too. Confirm the separate-limit mechanic and each plan's current-year figure with your plan administrator.

Not capturing an available employer match. Where a 403(b) plan offers an employer match, leaving that match uncaptured by contributing too little is generally a larger cost than any fee difference between investment options within the plan.

Ignoring plan portability rules when changing employers. Not every 403(b) accepts incoming rollovers, and some legacy annuity contracts carry surrender charges for moving money out early. Review a plan's specific rollover and surrender terms before assuming a balance can move freely.

Decision Checklist

• Does my employer offer a 403(b) match, and am I contributing enough to capture the full match before directing savings elsewhere?
• Does my plan offer a custodial mutual-fund account, an annuity contract, or both, and what are the expense ratios and any surrender charges on each option?
• Does my plan offer a Roth 403(b) option, and does my current versus expected future tax rate favor pre-tax or Roth deferrals?
• Do I also have access to a 457(b) through the same employer, and am I taking advantage of the separate contribution limit rather than assuming the two plans share one cap?
• Am I eligible for the 15-years-of-service catch-up, and does my plan permit it?
• If I'm changing employers, what are my plan's specific rollover and surrender terms for moving the balance?

Frequently Asked Questions

References

This guide is based on publicly available IRS guidance as of August 2026. Key sources include:

• IRS: IRC 403(b) Tax-Sheltered Annuity Plans: eligibility, permitted investment vehicles (annuity contracts, custodial accounts, retirement income accounts), and plan structure.
• IRS: Retirement Topics: 403(b) Contribution Limits: the 403(b) elective deferral limit, the 15-years-of-service catch-up mechanics, and the exclusion of 457 plans from 403(b) contribution aggregation.
• IRS: Publication 571, Tax-Sheltered Annuity Plans (403(b) Plans): comprehensive rules for 403(b) contributions, distributions, and rollovers.
• IRS: Retirement Topics: Required Minimum Distributions (RMDs): RMD rules applicable to traditional and Roth 403(b) balances.

This content was reviewed by the Swoopr Editorial Team in August 2026 and reflects publicly available information at that time. Tax law and plan-specific rules are subject to change; verify current limits, plan menus, and rules directly with your plan administrator, the IRS, or a qualified tax professional before making contribution or rollover decisions.

Conclusion

A 403(b) plan gives public-school, nonprofit, and certain ministerial employees a tax-advantaged retirement savings vehicle that is, at its core, taxed the same way as the far more familiar 401(k). The meaningful differences sit in the details: who can sponsor the plan, what investment vehicles the plan is allowed to hold and what a specific employer actually offers, whether ERISA applies, and a genuinely useful contribution mechanic for employees who also have access to a 457(b). None of that changes the fundamental math of tax-advantaged saving, but it does mean a 403(b) participant benefits from checking the specifics of their own plan rather than assuming it behaves exactly like a colleague's 401(k) in the private sector.