A worker who starts a job at a newer company now begins saving for retirement automatically, whether or not they ever fill out a form. Under a rule in effect for plan years that began after 2024, most 401(k) and 403(b) plans created in the last few years must enroll new hires at a contribution rate between 3% and 10% of pay and raise that rate over time. The change is designed to fix a stubborn problem in American retirement: too many people who intend to save never get around to signing up, and the years of compounding they lose are impossible to recover later.
How the SECURE 2.0 auto-enrollment mandate works
The requirement comes from the SECURE 2.0 Act, the 2022 retirement law, and it took effect for plan years beginning after December 31, 2024. Affected employers must automatically enroll each eligible new employee at an initial deferral rate of at least 3% but no more than 10% of compensation. That contribution then rises by one percentage point at the start of each year until it reaches at least 10%, and not more than 15%, of pay. The money goes into the worker’s own account, invested according to the plan’s default option.
Crucially, the mandate does not force anyone to save. A newly hired worker who does not want to participate, or who prefers a different percentage, can opt out or change the rate at any time, and some plans even refund contributions made in the first 90 days for employees who back out quickly. The Internal Revenue Service’s retirement plan guidance lays out these features, which the agency has been detailing through proposed regulations as employers adjust their systems. The design leans on inertia in the saver’s favor, flipping the default from “opt in” to “opt out.”
That reversal is the whole point. Behavioral research has long shown that participation jumps dramatically when enrollment is automatic, because the effort of doing nothing now leads to saving rather than to sitting on the sidelines.
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Which plans are covered and which are exempt
The rule applies only to plans established after the SECURE 2.0 Act was signed on December 29, 2022, which is why it is often described as a mandate for newer plans. Any 401(k) or 403(b) plan that already existed on that date is exempt and can continue operating as it did before, even if it never adopted automatic enrollment. That distinction matters for older workers and their adult children alike, because whether a paycheck starts saving on its own depends entirely on how recently the employer’s plan was set up.
Several categories of employer are carved out regardless of when their plan began. As benefits advisers at Mercer have outlined, the requirement generally does not reach businesses with 10 or fewer employees, companies less than three years old, governmental and church plans, or SIMPLE 401(k) arrangements. The exemptions are meant to spare the smallest and newest employers the administrative cost of building an automatic system, though those workers can still enroll on their own.
The result is a patchwork. Two people starting jobs on the same day can face very different defaults, one saving automatically and the other left to sign up, based purely on the age and size of each employer’s plan.
Workers can find out which situation applies to them by asking their employer’s human resources or benefits department, or by reading the plan’s summary description. Even at an exempt employer, signing up voluntarily and setting a contribution rate takes only a short form, and doing so captures any matching contribution the company offers. That single step can be worth more than the automatic feature itself, since an unclaimed match is money the employer was prepared to hand over for free.
What automatic saving means for a worker’s balance
For the employee, the practical effect is a paycheck that quietly builds a nest egg from day one. A worker earning $50,000 who is enrolled at 3% sets aside $1,500 in the first year before any employer match, and the annual one-point increases push that figure higher without any decision being made. Over a career, the gap between starting to save immediately and starting years later can amount to tens of thousands of dollars, because the earliest contributions have the longest time to grow.
The automatic design also affects family conversations across generations. Older parents helping a grandchild or a late-career relative think through finances can point out that a default rate is a floor, not a target, and that capturing a full employer match usually requires contributing more than the starting 3%. Checking the deferral rate and the invested default option is worth doing even when enrollment happens on its own.
The mandate arrives alongside other SECURE 2.0 changes reshaping workplace saving, from higher catch-up contributions for workers in their early 60s to a new option that lets employers match student-loan payments with retirement contributions. Together they push the retirement system toward enrolling and keeping more people in it by default. For an older worker changing jobs late in a career, automatic enrollment means even a short final stint can quietly add a few thousand dollars to a balance that will soon be drawn down.
The broader significance is a slow shift in how Americans back into retirement security. By making saving the path of least resistance for a growing share of new workers, the mandate does not guarantee a comfortable retirement, but it closes the most common gap of all: the years lost by people who meant to start and simply never did.
This article was produced with AI assistance and reviewed by The Money Overview editorial team.
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