Why Do Some 403(b) Plans Offer Annuities Instead of Mutual Funds?

Updated July 9, 2026 6 min read

It can seem odd that a retirement plan aimed at teachers, nurses, and nonprofit employees would lean so heavily on insurance products, until you look at how the 403(b) was actually written into the tax code in the first place.

The short answer

Section 403(b) of the tax code was originally built specifically around annuity contracts issued by insurance companies, which is why annuities remain a common, sometimes default, investment option in many of these plans today. Mutual fund custodial accounts were added to the available structure later, so current plans often mix both, but the annuity option persists partly because it was there first and partly because some employers and providers have kept those arrangements in place.

How the plan type originated

When this section of the tax code was created, the vehicle available for tax-deferred contributions by employees of schools and certain nonprofit organizations was specifically an annuity contract, not a mutual fund account. Insurance companies were the natural providers of that structure, which is why so many long-standing 403(b) plans still have deep relationships with insurance companies rather than mutual fund companies alone. Understanding this history helps explain why 403(b) investment menus can look different from a typical 401(k), which was never built around an annuity requirement in the same way.

Why annuity contracts stuck around after mutual funds became available

Once mutual fund custodial accounts became a permitted structure within 403(b) plans, many employers had the option to add fund-based investing alongside or instead of the original annuity contracts. Some did, and some didn’t, often depending on which providers the employer already had relationships with and how much administrative effort it took to bring on a new type of investment option. Older, well-established relationships with insurance companies, combined with the features some annuity contracts offer, like a contractually stated minimum payout, meant many employers simply kept the annuity option rather than replacing it outright.

What features an annuity contract can add

How this shapes the participant experience

For someone enrolled in a 403(b) with an annuity-heavy menu, this history means the available options may look and behave differently than what a friend with a 401(k) is choosing from, even though both are saving under similar tax rules. It also means cost comparisons take a bit more digging, since an annuity contract’s total cost includes both the investment expense and any insurance-related charges, and those aren’t always presented side by side as clearly as a simple fund expense ratio.

Questions worth asking before choosing

What to weigh

The annuity-first design of 403(b) plans is a product of tax-code history rather than a judgment about which structure is better, and today’s plans often blend both annuity contracts and mutual fund accounts. Reading what a specific contract charges and promises, and comparing it against any fund-based alternative in the same plan, is the practical way to make sense of a menu shaped by decades-old rules.