Defined Benefit vs. 401(k): What You're Actually Getting

Updated Jun 2024

The shift from defined benefit pensions to 401(k) plans has been one of the most consequential changes in American retirement over the past 40 years. About 80% of private-sector workers with employer retirement benefits now have only a 401(k), compared to the 1980s when most had a traditional pension. But the two plans work so differently that comparing them requires looking at risk, cost, income, and who really benefits.

How Each Plan Works

A defined benefit plan promises a specific monthly payment at retirement, calculated by a formula — typically a percentage of your final average salary multiplied by years of service. A worker with 30 years of service under a 2% formula earning $80,000 would receive $48,000 per year for life. The employer funds the plan, manages the investments, and bears all the risk of meeting that promise.

A 401(k) plan is a savings account where the employee contributes a portion of each paycheck (up to $23,000 in 2024, plus $7,500 if over 50) and the employer may or may not match some portion. The employee chooses the investments and bears all the risk. At retirement, the account balance is whatever was contributed and however the investments performed. There is no guaranteed amount.

Risk: Who Bears It Matters

The fundamental difference is risk allocation. In a pension, the employer assumes investment risk, longevity risk (the risk you live longer than expected), and inflation risk (if the plan has a COLA). In a 401(k), the employee bears all three. This distinction has enormous practical consequences. A pension participant who lives to 95 continues receiving full payments. A 401(k) participant who lives to 95 may run out of money entirely — what retirement researchers call "longevity risk," and what retirees call a crisis.

Investment risk is equally asymmetric. A pension plan with professional managers, diversified portfolios, and a multi-decade time horizon can weather market downturns that devastate individual 401(k) accounts. During the 2008 financial crisis, the average 401(k) balance dropped 31%. Pension beneficiaries, by contrast, continued receiving their full monthly payments without interruption.

The Numbers: What Each Actually Delivers

Consider a career employee earning $75,000 who works for 30 years. Under a typical pension formula (2% per year of service), they would receive $45,000 per year for life — a 60% income replacement rate. Under a 401(k) with a 6% contribution, 50% employer match, and 7% annual returns, the same employee would accumulate roughly $680,000. Using the 4% withdrawal rule, that generates about $27,200 per year — a 36% income replacement rate, barely half what the pension provides. And the 401(k) can be depleted; the pension cannot.

The gap widens at lower incomes because the pension formula replaces a higher percentage of salary for workers who cannot afford to maximize 401(k) contributions. It also widens for long-tenure employees because the pension formula rewards years of service linearly while 401(k) growth depends heavily on early contributions and compound returns that many workers miss by starting late.

Cost to the Employer

Employers shifted to 401(k) plans primarily to reduce cost and volatility. A defined benefit pension typically costs the employer 15-25% of payroll (normal cost plus amortization of unfunded liabilities). A typical 401(k) match costs 3-6% of payroll. The savings are substantial and predictable, which is why corporate CFOs and budget officers prefer them. However, the lower cost reflects a lower benefit — the retirement income risk has been transferred to employees, not eliminated.

Portability and Job Changes

One genuine advantage of 401(k) plans is portability. The account balance follows you from job to job with no loss of value. Pensions penalize job changers because the benefit formula typically uses final average salary — leaving a job at age 35 means your pension is calculated on your age-35 salary, not the much higher salary you would earn at retirement. For workers who change jobs every 4-5 years, 401(k) plans often deliver comparable or even better outcomes than pensions. For career employees who stay 20-30 years, the pension is almost always superior.

What About Hybrid Plans?

Hybrid plans like cash balance plans attempt to combine the best features of both designs. They provide a guaranteed minimum return (reducing employee risk) while offering a portable lump-sum balance (reducing job-change penalties). Several states have adopted hybrid designs for new public employees, pairing a smaller defined benefit pension with a mandatory defined contribution component. These designs are a pragmatic compromise, though they typically provide less generous retirement income than a full traditional pension.

The Funding Question

The biggest caveat for pension advocates is funding. A pension is only as good as the money behind it. Across the 151 plans PensionWatch tracks, the average funding ratio is 73.4%, with total unfunded liabilities of $1963.6B. An underfunded pension creates real risk for participants, particularly in plans without PBGC coverage. A fully funded pension is clearly superior to a 401(k) for retirement security. An underfunded pension with a declining trend carries risks that a well-managed 401(k) does not.

The Bottom Line

For most workers, a well-funded defined benefit pension provides significantly more retirement income and security than a 401(k). The typical pension replaces 50-70% of pre-retirement income for life, while the typical 401(k) replaces only 30-40% and can be exhausted. However, the decline of pensions in the private sector means most workers now have only a 401(k) available to them. If that describes you, maximizing your contributions, taking full advantage of any employer match, keeping fees low, and avoiding early withdrawals are the most impactful steps you can take to close the gap.