The core difference between a 401(a) and a 403(b) is who funds the account and whether you have a choice. A 401(a) plan is an employer-sponsored retirement plan used mainly by government agencies and some nonprofits, where the employer sets the rules and contributions are often mandatory. A 403(b) plan is a tax-sheltered annuity offered by public schools, 501(c)(3) tax-exempt organizations, and churches, funded primarily through voluntary salary deferrals you choose to make. Both grow tax-deferred, both have the same retirement-age rules, and both cap total annual contributions at the same dollar figure, but the day-to-day experience of participating in each is quite different.
Who Offers Each Plan
A 401(a) plan can be established by state and local government entities, including public agencies, fire districts, school districts acting as employers, and municipal departments, along with certain tax-exempt organizations. Eligibility hinges on your employer’s legal status, not your job title. State and local governments are barred from including a cash-or-deferred (elective deferral) arrangement in a 401(a) plan, which is why these plans typically run on employer and mandatory employee contributions instead of voluntary paycheck deferrals.1Office of the Law Revision Counsel. 26 USC 401 – Qualified Pension, Profit-Sharing, and Stock Bonus Plans
A 403(b) plan is available to employees of public school systems and to organizations holding tax-exempt status under Section 501(c)(3), including hospitals, charitable foundations, and research institutions. Self-employed ministers and chaplains qualify under a separate provision even if their employer is not a 501(c)(3).2Office of the Law Revision Counsel. 26 USC 403 – Taxation of Employee Annuities Employers must follow a “universal availability” rule: if any employee can make salary deferrals, the opportunity generally has to be open to all employees. Certain categories may be excluded, including workers who typically put in fewer than 20 hours per week, some student workers, and nonresident aliens.3Internal Revenue Service. Issue Snapshot – 403(b) Plan – The Universal Availability Requirement
Who Puts Money In
Participation in a 401(a) plan is often a condition of employment. When the plan requires mandatory contributions, you generally cannot opt out. The contribution rate is written into the plan document, and both you and the employer follow it from your first paycheck. That produces a predictable funding structure and pushes every eligible worker to build savings on the same schedule.
A 403(b) works the opposite way. You choose whether to participate by signing a salary reduction agreement, and you can start, stop, or change your contribution amount during the year. Your employer has to give you the chance to participate, but it cannot force you to contribute your own wages. That flexibility helps your monthly budget but shifts the responsibility for saving onto you.
How Much You Can Contribute in 2026
For a 403(b), the number that matters most is the elective deferral limit, since the plan runs on your salary contributions. In 2026 you can defer up to $24,500. If you’re 50 or older, you can add $8,000 in catch-up contributions, for a total of $32,500. Under SECURE 2.0, participants aged 60 through 63 get an enhanced catch-up of $11,250 instead of $8,000, allowing a total deferral of up to $35,750 during that age window.4Internal Revenue Service. 401(k) Limit Increases to $24,500 for 2026, IRA Limit Increases to $7,500
A 403(b) also carries a catch-up rule you won’t find in a 401(a). If you’ve worked at least 15 years for the same qualifying employer, such as a public school system, hospital, or church, you can raise your deferral limit by up to $3,000 per year, with a $15,000 lifetime cap.5Internal Revenue Service. Retirement Topics – 403(b) Contribution Limits It stacks with the age-based catch-up, so a qualifying 50-year-old with 15 years of service could potentially defer up to $35,500 in a single year. The 15-year catch-up is applied before the age-50 catch-up when your limit is calculated.6Internal Revenue Service. 403(b) Plans – Catch-Up Contributions
For a 401(a), the more relevant ceiling is the total annual addition limit under Section 415(c) because contributions are mostly coming from the employer. In 2026, combined employer and employee contributions cannot exceed $72,000 or 100% of your compensation, whichever is less. The compensation used in that calculation is capped at $360,000.7Internal Revenue Service. COLA Increases for Dollar Limitations on Benefits and Contributions The same $72,000 total-addition cap applies to a 403(b) once employer contributions are counted, though most 403(b) participants focus on the elective deferral limit since that’s the portion they actually control.
Vesting: What You Actually Own
Any money you personally contribute is always 100% yours immediately, whether it went in as a mandatory contribution to a 401(a) or a voluntary deferral to a 403(b). You never lose your own contributions.
Employer contributions are a different question. In a 401(a), the employer sets a vesting schedule that determines when its contributions become yours. Common structures include cliff vesting, where you go from 0% to 100% after a set number of years, and graded vesting, where your vested share climbs each year. A typical graded schedule might vest 20% after two years and add another 20% each year until you reach full ownership at six.8Internal Revenue Service. Change in Plan Vesting Schedules Leave before you’re fully vested and you forfeit the unvested employer money.
A 403(b) can also apply a vesting schedule to employer matching or non-elective contributions. Your own elective deferrals, though, are always immediately vested. Since employee deferrals are usually the bulk of a 403(b) account, most of the balance belongs to you from day one.
What You Can Invest In
A 403(b) account is limited to three types of vehicles: an annuity contract purchased through an insurance company, a custodial account holding mutual funds, or, for church employees only, a retirement income account that may hold annuities or mutual funds. Life insurance contracts issued after September 2007 are not allowed.9Internal Revenue Service. IRC 403(b) Tax-Sheltered Annuity Plans
A 401(a) usually offers a broader menu. The employer or a fiduciary board picks the available options, which can include mutual funds, target-date funds, stable value funds, and sometimes a self-directed brokerage window. You choose from what the plan offers, and unless a brokerage option exists, you can’t reach outside the menu.
Getting Money Out Before Retirement
Both accounts are built for the long term, and pulling money out early is expensive. A distribution before age 59½ triggers a 10% additional tax on top of the regular income tax owed on the withdrawal.10Internal Revenue Service. Retirement Topics – Exceptions to Tax on Early Distributions Public safety employees in governmental 401(a) plans get a notable exception: if you’re a qualified public safety employee who separates from service during or after the year you turn 50, or after 25 years of service, whichever comes first, you can take penalty-free distributions from that plan.11Internal Revenue Service. Topic No. 558, Additional Tax on Early Distributions from Retirement Plans Other Than IRAs
A 403(b) plan may allow hardship withdrawals from your elective deferral account if you face an immediate and heavy financial need such as unreimbursed medical costs, funeral expenses, or costs to prevent eviction.12Internal Revenue Service. Dos and Donts of Hardship Distributions The amount is limited to what’s necessary to meet the need, and the plan itself has to permit hardship distributions.13Internal Revenue Service. Hardships, Early Withdrawals and Loans Hardship money is taxed as ordinary income and can still trigger the 10% penalty if you’re under 59½.
A 401(a) generally does not offer hardship withdrawals. Most governmental 401(a) plans require a triggering event, typically separation from service through resignation, retirement, or termination, before you can access the money. Some plans permit in-service distributions once you hit a specified age, but that depends entirely on the plan document.14Internal Revenue Service. Governmental Plans Under Internal Revenue Code Section 401(a)
Loans are possible from either plan if the plan document allows them. The maximum is the lesser of 50% of your vested balance or $50,000, generally repaid within five years with at least quarterly payments. A longer repayment period applies if the loan buys your primary residence.15Internal Revenue Service. Retirement Topics – Loans Because you’re borrowing from yourself and paying yourself back with interest, a loan repaid on schedule avoids the penalty and income tax that would hit a withdrawal.
Rollovers When You Leave
When you separate from your employer, either account can be rolled into a traditional IRA, a Roth IRA (with tax owed on the conversion), or another employer’s eligible plan. A direct rollover, moving the funds straight from old plan to new, is the cleanest route because it avoids the mandatory 20% federal income tax withholding that applies when the money is paid to you first.16Internal Revenue Service. Topic No. 413, Rollovers from Retirement Plans If you take the distribution yourself, 20% will be withheld even if you plan to redeposit into an IRA within 60 days. To defer tax on the full amount, you’d have to make up that 20% from other funds. The receiving plan also isn’t required to accept a rollover, so confirm with the new administrator before you initiate anything.17eCFR. 26 CFR 1.401(a)(31)-1 – Requirement to Offer Direct Rollover of Eligible Rollover Distributions
Required Minimum Distributions
Both plans require you to start taking required minimum distributions at age 73.18Internal Revenue Service. Retirement Plan and IRA Required Minimum Distributions FAQs If you’re still working past that age and your plan allows it, you may delay RMDs from your current employer’s plan until you actually retire. That exception does not extend to IRAs or plans from prior employers. Under SECURE 2.0, the starting age rises to 75 beginning in 2033. Missing an RMD costs 25% of the amount you should have withdrawn, dropping to 10% if you catch and correct the shortfall within two years.19Internal Revenue Service. Retirement Topics – Required Minimum Distributions (RMDs)
Quick Comparison for 2026
- Eligible employers: 401(a) covers government agencies and certain nonprofits; 403(b) covers public schools, 501(c)(3) organizations, and churches.
- Participation: 401(a) is often mandatory; 403(b) is voluntary through salary deferral.
- 2026 employee deferral limit: 401(a) typically has no elective deferral option; 403(b) is $24,500.
- 2026 total addition limit: Both are $72,000, or 100% of compensation if less.
- Age 50+ catch-up: 403(b) is $8,000, rising to $11,250 for ages 60–63.
- 15-year service catch-up: 403(b) only, up to $3,000 per year with a $15,000 lifetime cap.
- Investment vehicles: 401(a) offers a broad employer-chosen menu; 403(b) is limited to annuities, mutual fund custodial accounts, or church retirement income accounts.
- Hardship withdrawals: Generally unavailable in a 401(a); available in a 403(b) if the plan permits.
- Loans: Both may allow loans up to $50,000 or 50% of the vested balance.
- RMD start age: Both begin at 73, rising to 75 in 2033.
One more thing worth checking before you plan around either account: state income tax treatment of retirement plan distributions varies widely. Some states fully exempt public retirement plan income, others offer partial exclusions based on age or income, and several have no personal income tax at all. Look up your state’s rules before estimating what you’ll actually keep.