403(b) vs 401(k): Key Differences for Retirement Planning

The Short Comparison

For the average participant, a 403(b) and 401(k) are functionally identical. Same contribution limits, same tax treatment, same early withdrawal rules, same RMD requirements. The differences matter mainly at the plan administration level and in investment options.

Who Gets Which Plan

403(b): Employees of:

• Public schools and universities
• Nonprofit organizations (501(c)(3))
• Hospitals and health systems
• Some church and government employers

401(k): Employees of for-profit private companies. Self-employed individuals can use a Solo 401(k).

You cannot choose between them — your employer determines which plan type they offer.

Contribution Limits: Identical

Both plans share the same IRS limits: $24,500 employee deferral for 2026, with catch-up contributions for eligible ages. If you have both a 403(b) and a 401(k) simultaneously (e.g., part-time work at two employers), the $24,500 limit applies across both combined.

Investment Options: The Real Difference

401(k): Can offer any SEC-registered security — index funds, ETFs, individual stocks (rare), bonds, REITs. Most large 401(k) plans offer low-cost index fund options.

403(b): By law, limited to:

• Annuity contracts (insurance company products)
• Custodial accounts holding regulated investment company shares (mutual funds)

This restriction historically caused 403(b) participants to be sold expensive variable annuities. Modern 403(b) plans now commonly offer mutual fund options, but many older or smaller nonprofit plans still only offer annuities with high expense ratios (1–2%+ per year). The fee drag over a 30-year career on a 1.5% annuity versus a 0.05% index fund can cost hundreds of thousands of dollars.

Employer Match: Converging

Historically, nonprofit employers offered smaller or no employer matches compared to for-profit 401(k) plans. This gap has narrowed:

• Large nonprofits (major hospitals, universities) now commonly match 3–6%
• Smaller nonprofits may offer 0–3% match or none
• Public school employees often have pension plans (defined benefit) alongside their 403(b), making a match less common

ERISA Coverage: A Significant Difference

ERISA (Employee Retirement Income Security Act) sets fiduciary standards for plan management, including rules requiring plan administrators to act in participants’ best interests and to offer sufficient investment choices at reasonable cost.

Most 401(k) plans are ERISA-covered. Many 403(b) plans are ERISA-exempt (particularly those of government employers and churches). This historically allowed 403(b) plans to be sold directly by insurance companies to employees without the same fiduciary oversight, contributing to the high-fee annuity problem.

ERISA-covered 403(b) plans (many large nonprofit hospitals and universities) have the same protections as 401(k) plans.

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

Unique to 403(b): employees with 15+ years of service with the same qualifying employer, who haven’t maximized contributions in prior years, may contribute an additional $3,000/year up to a $15,000 lifetime maximum. This provision has no equivalent in 401(k) plans.

Which Is Better?

Neither plan is inherently better — plan quality depends on:

1. Investment options offered (low-cost index funds vs. expensive annuities)
2. Employer match generosity
3. ERISA coverage (fiduciary protections)

Evaluate your specific plan by checking the expense ratios of available funds. A 403(b) with low-cost index funds is equal to or better than a 401(k). A 403(b) with only variable annuities charging 1.5% annually is significantly worse over a long career.

If you have a choice between a nonprofit and for-profit employer otherwise equal, the retirement plan quality matters — check both plans’ investment menus before accepting an offer.