Defined Benefit vs. Cash Balance vs. 401(k): How the Plan Types Differ for Administrators

9/22/2026

Most comparisons of retirement plans are written for the business owner deciding which one to adopt: how much can be contributed, how much is deductible, who bears the investment risk. This one is written for the people who have to run the plan once it exists. A 401(k), a traditional defined benefit plan and a cash balance plan look very different from the payroll desk and the benefits office. They need different data, run on different calendars, involve different outside professionals and carry different penalties when something is missed.

If your employer is adding a cash balance plan next to its 401(k), or you have inherited a frozen pension along with the 401(k), this is the map.

The Three Plan Types in One Paragraph Each

401(k) plan. A defined contribution plan. Each participant has an individual account funded by their own pre-tax or Roth deferrals and any employer contributions. The benefit is whatever the account is worth. Investment risk sits with the participant. The employer's obligation is to run the plan according to its document: take the right deferrals, deposit them on time, apply the right match.

Traditional defined benefit (DB) plan. The plan promises a benefit at retirement, usually a monthly annuity calculated by formula (for example, a percentage of final average pay times years of service). Assets are pooled in a trust. The employer must fund the promise, and if investments underperform, the employer makes up the difference. Investment and longevity risk sit with the employer.

Cash balance plan. Legally a defined benefit plan, but the benefit is expressed as a hypothetical account. Each year the participant's account is credited with a pay credit (such as a percentage of compensation or a flat dollar amount) and an interest credit (a fixed rate or a rate tied to an index), according to the plan's formula. Participants see an "account balance," but there are no individual investment accounts. The assets are pooled and invested by the plan, and the employer still bears the investment risk. Because it is a defined benefit plan, it is funded, actuarially valued and, in most cases, insured by the Pension Benefit Guaranty Corporation (PBGC).

Side-by-Side: What Changes for the Administrator

Feature	401(k)	Traditional DB	Cash balance
Legal type	Defined contribution	Defined benefit	Defined benefit
Who funds it	Employees, plus any employer contributions	Employer	Employer
Who bears investment risk	Participant	Employer	Employer
How the benefit is stated	Actual account balance	Formula annuity at retirement	Hypothetical account balance
Annual actuarial valuation	No	Yes	Yes
Minimum funding rules	No (money purchase plans aside)	Yes	Yes
PBGC coverage and premiums	No	Most plans	Most plans
Annual limit (2026)	$24,500 deferral; $72,000 total annual additions	$290,000 annual benefit	$290,000 annual benefit
Typical vesting of employer money	Plan schedule (immediate for traditional safe harbor)	Plan schedule within ERISA maximums	Full vesting after 3 years of service
Form 5500 schedules specific to plan type	None	Schedule SB, Schedule R	Schedule SB, Schedule R

 

The 2026 dollar limits come from IRS Notice 2025-67. The defined benefit limit is expressed as an annual benefit, not a contribution, which is why a cash balance plan can absorb far larger contributions for older owners than a 401(k) can.

Funding: Where the Work Is Most Different

401(k): contributions follow payroll

In a 401(k), money moves into the plan in step with payroll. Employee deferrals are withheld every pay period and become plan assets once they can reasonably be segregated from the employer's general assets. Employer contributions follow the plan's formula and schedule. The funding question each pay period is simple: did the right amount go in, on time? Our 401(k) plan administration handbook covers deposit timing in detail.

Defined benefit and cash balance: contributions follow the actuary

In a defined benefit plan, contributions are not set by payroll at all. Each year an enrolled actuary values the plan's liabilities and assets and determines the minimum required contribution under Code section 430 (the single-employer funding rules). There is usually also a maximum deductible contribution, and the range between the two is where a sponsor chooses how much to put in.

Key administrative points:

• The minimum required contribution for a plan year is generally due no later than 8½ months after the plan year ends.
• Quarterly installments. A plan that had a funding shortfall in the prior year generally must make quarterly contributions during the year. Missed installments carry interest and can trigger reporting.
• Excise tax. Unpaid minimum required contributions trigger an excise tax under Code section 4971.
• Benefit restrictions. Under Code section 436, a single-employer plan whose funded percentage, as certified by the actuary, falls below specified levels may be restricted from paying lump sums, adopting benefit increases or continuing accruals. The administrator must know the certified percentage before processing distributions.

Payroll's role in funding is indirect but essential: the actuary's valuation runs on the compensation, service and demographic data payroll provides. Wrong data means a wrong funding number.

Cash balance alongside a 401(k)

Cash balance plans are frequently added to an existing 401(k), often in professional practices where owners want to contribute more than the defined contribution limits allow. The two plans are typically tested together for nondiscrimination, and the cash balance pay credits for rank-and-file staff are often designed alongside a profit-sharing or safe harbor contribution in the 401(k). That makes the two plans one design. A change in one, such as a new profit-sharing allocation, can affect whether the combined arrangement passes.

Actuarial and Testing Work

401(k). Annual ADP/ACP testing (unless the plan is safe harbor), top-heavy testing, coverage testing and annual limit checks. The TPA runs these from the payroll census. No actuary is needed.

Traditional DB and cash balance. An annual actuarial valuation, a Schedule SB signed by the enrolled actuary and filed with the Form 5500, and nondiscrimination testing of benefits under Code section 401(a)(4). Defined benefit plans must also satisfy the minimum participation rule of Code section 401(a)(26): on each day of the plan year, the plan must benefit at least the lesser of 50 employees or 40% of the employer's employees (with a special rule for very small employers). A cash balance plan designed to benefit mostly owners can run into this rule as headcount changes.

Cash balance specifically. The interest crediting rate must meet regulatory limits so that it does not exceed a market rate of return, and the plan must satisfy the defined benefit accrual rules. Benefits must be fully vested after three years of service. These are design constraints the actuary and plan document handle, but the administrator should know they exist, because a request to "just change the interest credit" or "vest people faster" is a plan amendment with actuarial consequences.

PBGC Premiums

Most private-sector defined benefit plans, including cash balance plans, are insured by the PBGC, and insured plans pay annual premiums. 401(k) plans are not PBGC-insured and pay no premiums.

For 2026 plan years, the PBGC's published single-employer rates are:

• Flat-rate premium: $111 per participant
• Variable-rate premium: $52 per $1,000 of unfunded vested benefits, capped at $751 per participant

The flat rate is paid for every participant, including retirees and terminated vested participants. That is one reason sponsors of frozen plans often offer lump-sum windows or purchase annuities to reduce headcount. The variable-rate premium depends on underfunding, so a well-funded plan may pay little or none.

Filing and due date. Premium filings are made electronically through PBGC's My Plan Administration Account (My PAA). For most plans the due date is the 15th day of the 10th full calendar month in the plan year, which is October 15 for a calendar-year plan. Note that this is measured from the start of the plan year, not the end, and that a Form 5500 extension does not extend PBGC premium filings.

Who is exempt from PBGC coverage. The PBGC lists exemptions including plans maintained by a professional service employer (such as a medical or law practice owned by professionals) that have never covered more than 25 active participants, and plans maintained exclusively for substantial owners. Many small-practice cash balance plans fall into one of these, which eliminates premiums but also eliminates PBGC insurance. Coverage status is a determination the plan's actuary or counsel should confirm, not an assumption.

Annual Reporting and Participant Disclosures

All three plan types file a Form 5500 (or 5500-SF if eligible), with these differences:

• Defined benefit and cash balance plans attach Schedule SB and generally Schedule R. A small DB plan that qualifies for the 5500-SF still attaches Schedule SB.
• Participant counts A 401(k) counts participants with account balances. A defined benefit plan counts all participants, including separated participants entitled to future benefits, which can push an older plan over the 100-participant line and into large-plan audit requirements.
• Form 8955-SSA applies to all three, reporting separated participants with vested benefits.
• Benefit statements. Defined contribution plans with participant-directed investments provide statements quarterly. Defined benefit plans, including cash balance, must generally provide a statement at least once every three years, or provide an annual notice that one is available.
• Annual funding notice. Defined benefit plans subject to PBGC coverage provide an annual funding notice to participants, beneficiaries and others, describing the plan's funded status.

Payroll Data: What Each Plan Needs

Data element	401(k)	Traditional DB	Cash balance
Compensation, by plan definition	Every payroll, for deferrals and match	Annually, for benefit accrual and funding	Annually or per period, for pay credits
Hours of service	Eligibility and vesting	Eligibility, vesting and benefit accrual	Eligibility, vesting and pay credit eligibility
Date of birth	Catch-up eligibility, distributions	Essential for actuarial valuation	Essential for actuarial valuation
Hire, termination and rehire dates	Eligibility, vesting, distributions	Service, vesting, breaks in service	Service, vesting, breaks in service
Marital status	Some distributions	Required for annuity and spousal consent	Required for annuity and spousal consent
Ownership and family relationships	HCE, key employee	HCE, key employee	HCE, key employee, often central to design

 

Three practical differences stand out.

Compensation accuracy matters more in a DB plan. In a 401(k), a compensation-definition error produces a missed deferral or match that can be corrected. In a final-average-pay DB plan, the same error changes the benefit itself and the funding valuation. In a cash balance plan, it changes the pay credit. For an owner in a cash balance plan, pay credits can be large, so small compensation errors become expensive.

Historical data matters. A DB plan needs service and pay history going back years, sometimes decades. Payroll system conversions that did not carry over history leave gaps the actuary will ask about.

Spousal rights apply more often. Defined benefit and cash balance plans must offer annuity forms of benefit, and the qualified joint and survivor annuity rules apply. Distributions in another form generally require spousal consent in a specific form. That makes marital status and spousal consent part of routine distribution processing, not an exception.

Choosing a Training Path

The work differs enough that each plan type has its own training. Payroll and HR professionals who run a 401(k) day to day start with the 401(k) Training and Certification Program. Those supporting a traditional pension can look at the Defined Benefit Training and Certification Program, and the Pension Benefit Guaranty Corporation course focuses on the PBGC side. Distribution processing in DB plans touches spousal consent, which has its own Spousal Rights and Consent Requirements Training and Certification Program.

Frequently Asked Questions

What is the difference between a cash balance plan and a 401(k)?

A 401(k) is a defined contribution plan. Participants have real individual accounts, funded mainly by their own deferrals, and they bear the investment risk. A cash balance plan is a defined benefit plan. The employer funds it, participants have hypothetical accounts credited with pay and interest credits set by the plan formula, and the employer bears the investment risk. Cash balance plans need annual actuarial valuations, are subject to minimum funding rules and are usually PBGC-insured. 401(k) plans need none of these.

Is a cash balance plan a defined benefit plan?

Yes. Although the benefit is expressed as an account balance, a cash balance plan is legally a defined benefit plan. The employer promises the pay and interest credits defined in the plan, regardless of how the plan's pooled assets perform. That means it is subject to the defined benefit rules: minimum funding, an annual actuarial valuation, Schedule SB with Form 5500, annuity and spousal consent rules, and, in most cases, PBGC coverage and premiums. Cash balance plans must fully vest participants after three years of service.

Can an employer have both a cash balance plan and a 401(k)?

Yes, and it is a common pairing, especially for professional practices where owners want to save more than the 401(k) limits allow. The two plans are usually designed and tested together for nondiscrimination, often with a safe harbor or profit-sharing contribution in the 401(k) for staff alongside cash balance pay credits. Because the plans are tested together, a change to one can affect the other. Payroll typically handles 401(k) deferrals every pay period and provides annual compensation data for the cash balance valuation.

What are the PBGC premium rates for 2026?

For single-employer plans with plan years beginning in 2026, PBGC publishes a flat-rate premium of $111 per participant and a variable-rate premium of $52 per $1,000 of unfunded vested benefits, capped at $751 per participant. The multiemployer flat rate is $40 per participant. Premiums are filed electronically through My PAA, generally by the 15th day of the 10th full calendar month of the plan year. Some small professional-service plans and owner-only plans are exempt from PBGC coverage and pay no premiums.

Do cash balance plans need an actuary?

Yes. As defined benefit plans, cash balance plans need an enrolled actuary to perform the annual valuation, determine the minimum required and maximum deductible contributions, certify the funded percentage for benefit restriction purposes, and sign Schedule SB for the Form 5500. The actuary also checks that the plan's interest crediting rate and benefit accruals meet the regulatory limits. A 401(k) plan does not need an actuary; its testing is usually handled by a third-party administrator using the payroll census.

Who bears the investment risk in a cash balance plan?

The employer does. Participants are promised the interest credit the plan specifies, whether that is a fixed rate or a rate tied to an index. If the plan's investments earn less than the promised credits, the shortfall shows up in the actuarial valuation and the employer's required contributions go up. If investments earn more, required contributions may fall. Participants' hypothetical balances do not rise or fall with the plan's actual investment results, which is the key difference from a 401(k) account.

Go Deeper on Cash Balance Administration

Cash balance plans combine defined benefit rules with an account-style presentation that participants, and sometimes payroll teams, mistake for a 401(k). The Cash Balance Plans Training and Certification Program focuses on that plan type. For the broader payroll context, see Payroll and Retirement Plans and this year's retirement plan contribution limits.

Limits and premium rates change every year. Confirm current figures with IRS and PBGC releases, and any plan-specific funding or coverage question with the plan's actuary.