Why Behavioral Features Are Becoming Central to Defined Contribution Plan Effectiveness
Despite broad adoption of employer-sponsored retirement plans, institutional research consistently highlights a gap between plan availability and participant retirement readiness. This gap has driven increasing attention toward plan design, specifically the behavioral features that shape how employees save, invest, and prepare for retirement.
Government agencies, regulatory bodies, and independent research organizations increasingly point to automatic enrollment, default investment design, and escalation policies as structural drivers of improved outcomes, not optional enhancements.
The Scale of Automatic Enrollment Adoption
The growth of automatic enrollment in defined contribution plans has been one of the most significant plan design trends of the past two decades.
According to Vanguard’s How America Saves 2025 report, 61% of Vanguard plans offered automatic enrollment in 2024, compared with just 10% in 2006. Among larger plans with 1,000 or more participants, adoption reached 78%.
The impact on savings behavior is substantial. Vanguard data indicates that employees in automatic enrollment plans saved an average of 12.3% of compensation (including employer contributions), compared to 7.4% in voluntary enrollment plans, a gap driven primarily by higher participation rates.
The SECURE 2.0 Act codified this trend into law, requiring all new 401(k) and 403(b) plans established after December 29, 2022, to implement automatic enrollment beginning with the 2025 plan year. Default contribution rates must be set between 3% and 10%, with mandatory annual escalation of at least 1% until the rate reaches between 10% and 15%.
Automatic Escalation and Savings Trajectory
Automatic enrollment addresses the participation gap. Automatic escalation addresses the adequacy gap.
Vanguard research found that participants enrolled in plans with both automatic enrollment and automatic annual increases save 20% to 30% more after three years than participants in plans with automatic enrollment alone. In 2024, 7 in 10 plans with 1,000 or more participants offered an automatic increase feature, and a record 45% of participants increased their deferral rate during the year.
The share of plans defaulting employees at 6% or higher has reached 30%, nearly double the level from a decade ago. Vanguard recommends a total savings rate of 12% to 15% of compensation as a benchmark for retirement readiness, and auto-escalation is among the most effective mechanisms for moving participants toward that threshold over time.
Default Investments and Professionally Managed Allocations
How contributions are invested is as consequential as whether they are made.
Target-date funds (TDFs) remain the dominant qualified default investment alternative (QDIA). According to PSCA survey data, TDFs serve as the QDIA in approximately 94% of plans. Vanguard reports that at year-end 2024, 67% of participants were invested in a professionally managed allocation, with 59% in a single target-date fund and 7% in a managed account advisory service.
The use of professionally managed allocations has grown by 50% over the past decade. Vanguard’s analysis shows that these solutions provide more age-appropriate equity exposure and continuous rebalancing, helping participants maintain diversified portfolios aligned to their retirement timeline.
The Department of Labor’s QDIA regulations, established under the Pension Protection Act of 2006, provide fiduciary safe harbor for plan sponsors who select and monitor these default options through a prudent process.
Engagement as a Complement to Automation
Research from both Fidelity and Vanguard indicates that while automatic features significantly improve baseline participation and savings behavior, ongoing engagement remains essential for optimizing outcomes.
Fidelity’s 16th annual Plan Sponsor Attitudes Study (2025) found that improved participant outcomes has been ranked as the top advisor value by plan sponsors for four consecutive years. Sponsor satisfaction with advisors is strongly correlated with perceived retirement readiness: 74% of sponsors who believed their participants were saving adequately reported high satisfaction, compared to 58% among those who did not.
These findings reinforce a broader institutional view that plan design and participant engagement are complementary, not substitutes. Automation establishes a floor, while education, guidance, and advice help participants make informed decisions over time.
Fiduciary and Governance Implications
The Department of Labor makes clear that plan sponsors retain fiduciary responsibility for plan design decisions, including the selection of default contribution rates, investment options, and escalation schedules.
Prudent process and documentation are central to fiduciary compliance. As SECURE 2.0 introduces new mandatory requirements for automatic enrollment, plan sponsors must ensure their governance structures are equipped to evaluate, implement, and monitor these features on an ongoing basis.
The ERISA Advisory Council has also begun exploring guidance on topics such as retirement income options within QDIAs and decumulation strategies, signaling that the regulatory landscape around plan design will continue to evolve.
Measuring Effectiveness Beyond Participation
Institutional evidence increasingly suggests that participation rates alone are an insufficient measure of plan effectiveness.
More meaningful indicators include contribution adequacy relative to income replacement targets, consistency of savings behavior over time, age-appropriateness of asset allocation, and participant confidence in retirement preparedness.
Plans that incorporate behavioral design features alongside ongoing education and advice are better positioned to demonstrate measurable progress across these dimensions.
Executive takeaway
Plan design is the most consequential lever available to plan sponsors seeking to improve retirement outcomes. Automatic enrollment, escalation, and well-monitored default investments establish a structural foundation, while participant engagement ensures that foundation translates into long-term readiness.
Better retirement outcomes start with better plan design. Whether you're a plan sponsor or a participant, Siebert has the tools and expertise to help.
Learn more at siebert.com/401k
- Vanguard — How America Saves 2025
https://corporate.vanguard.com/content/corporatesite/us/en/corp/articles/how-america-saves-2025-key-trends-insights.html - Vanguard — Preview: How America Saves 2025
https://workplace.vanguard.com/insights-and-research/report/previewing-how-america-saves-2025.html - Vanguard — How America Nudges Employees to Save for Retirement
https://workplace.vanguard.com/insights-and-research/perspective/how-america-nudges-employees-to-save-for-retirement.html - Fidelity Investments — 16th Annual Plan Sponsor Attitudes Study (2025)
https://newsroom.fidelity.com/pressreleases/advisor-insights-help-plan-sponsors-simplify-complexity--according-to-16th-fidelity--plan-sponsor-at/s/cfb3bce2-b93b-42b5-bf99-47437354f75f - U.S. Department of Labor — Automatic Enrollment 401(k) Plans for Small Businesses
https://www.dol.gov/agencies/ebsa/about-ebsa/our-activities/resource-center/publications/automatic-enrollment-401k-plans - U.S. Department of Labor — Meeting Your Fiduciary Responsibilities
https://www.dol.gov/agencies/ebsa/about-ebsa/our-activities/resource-center/publications/meeting-your-fiduciary-responsibilities - Groom Law Group — IRS Issues Guidance on Mandatory Automatic Enrollment (Jan 2025)
https://www.groom.com/resources/irs-issues-guidance-on-mandatory-automatic-enrollment/ - Plan Sponsor Council of America — Reconsidering TDFs as the QDIA (2024)
https://www.psca.org/news/psca-news/2024/4/reconsidering-tdfs-qdia/ - Fiduciary/Industry Commentary — 2024 QDIA Recommendations and Trends
https://www.fiducientadvisors.com/research/the-evolution-of-qualified-default-investment-alternatives-key-developments-and-trends-in-2024
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