Do employers have to contribute to a 401(k)? For a standard traditional 401(k), no: federal law lets a company offer the plan without putting in a single dollar of its own. That default flips in three situations. If the employer runs a Safe Harbor 401(k), sponsors a SIMPLE IRA, or lets the plan become top-heavy, contributions stop being optional and become a legal requirement backed by tax penalties.
Traditional 401(k): Employer Contributions Are Optional
The Employee Retirement Income Security Act of 1974 sets minimum standards for private retirement plans, but it does not force any company to offer one.1Legal Information Institute. ERISA When an employer does set one up, ERISA still does not require a match or any other employer deposit. The plan document decides, and the document is allowed to say contributions are entirely discretionary.
Discretionary means what it sounds like. An employer can match 50% of employee deferrals one year, drop to 25% the next, and skip the match the year after. The IRS lets employers make non-elective contributions for all participants, profit-sharing contributions tied to company performance, or nothing at all.2Internal Revenue Service. Retirement Topics – Contributions Oversight focuses on fiduciary duties and plan administration, not on forcing anyone to fund accounts.
That is why your Summary Plan Description matters. It tells you whether your employer has locked in a specific match formula or kept the right to change it. If it says “discretionary,” assume nothing is guaranteed from one year to the next.
Safe Harbor 401(k): A Required Formula Every Year
A Safe Harbor 401(k) is the clearest case where contributions are mandatory. In exchange for skipping the non-discrimination testing that trips up many traditional plans, the employer commits to one of three contribution formulas and must fund it every year.
Basic Match
The employer matches 100% of the first 3% of pay the employee defers, plus 50% of the next 2%. Contribute 5% of your salary and your employer puts in the equivalent of 4%. Contribute less, and the match shrinks proportionally.
Enhanced Match
The employer can design a more generous formula, so long as it is at least as generous as the basic match at every tier and does not require employees to defer more than 6% of pay to get the full match. A dollar-for-dollar match on the first 6% of pay is a common version.
Non-Elective Contribution
Instead of matching, the employer deposits at least 3% of each eligible employee’s compensation, whether or not the employee contributes anything. It goes to everyone who meets the plan’s eligibility rules.
All three formulas share a feature that matters a lot: Safe Harbor contributions are 100% vested the moment they land in your account. There is no waiting period. The employer also has to send eligible employees a written notice between 30 and 90 days before the start of each plan year, explaining the formula and employee rights.3Internal Revenue Service. Notice Requirement for a Safe Harbor 401(k) or 401(m) Plan Missing that window can cost the plan its Safe Harbor status for the year.
SIMPLE IRA: Mandatory Employer Funding Every Year
Businesses with 100 or fewer employees earning at least $5,000 in the prior year can set up a Savings Incentive Match Plan for Employees, or SIMPLE IRA.4U.S. Department of Labor. SIMPLE IRA Plans for Small Businesses A SIMPLE IRA removes employer discretion entirely. The employer must contribute every year and chooses between two formulas:
- A dollar-for-dollar match of what the employee contributes, capped at 3% of the employee’s pay. An employee earning $50,000 who contributes $2,500 gets a $1,500 employer match. If the employee contributes nothing, the employer owes nothing that year.
- A 2% non-elective contribution for every eligible employee, whether or not the employee contributes. For 2026, the compensation counted toward this calculation is capped at $360,000.5Internal Revenue Service. COLA Increases for Dollar Limitations on Benefits and Contributions
These rules sit in the Internal Revenue Code, not just the plan document. An employer cannot skip a year without violating federal law and risking plan disqualification.6Internal Revenue Service. Retirement Topics – SIMPLE IRA Contribution Limits Employer contributions to a SIMPLE IRA are also 100% vested immediately.
Top-Heavy Plans: A Minimum Contribution Kicks In
A plan that mostly benefits owners and highly paid executives triggers its own mandatory contribution rule. Under Internal Revenue Code Section 416, a 401(k) is “top-heavy” when more than 60% of total account balances belong to key employees.7Office of the Law Revision Counsel. 26 USC 416 – Special Rules for Top-Heavy Plans For 2026, a key employee is generally an officer earning more than $235,000, a more-than-5% owner, or a more-than-1% owner earning over $150,000.8Internal Revenue Service. 2026 Amounts Relating to Retirement Plans and IRAs
Once a plan is top-heavy, the employer must contribute at least 3% of annual compensation for every non-key employee, even employees who did not defer any of their own pay that year.7Office of the Law Revision Counsel. 26 USC 416 – Special Rules for Top-Heavy Plans One exception: if the highest contribution rate for any key employee is less than 3%, the employer can use that lower rate for everyone else.
The status is tested each year using account balances as of the “determination date,” which is the last day of the preceding plan year. For a new plan, the determination date is the last day of its first plan year.9eCFR. 26 CFR 1.416-1 – Questions and Answers on Top-Heavy Plans A small company can pass the test for several years and then tip over the 60% line as owner balances grow faster than rank-and-file balances.
Vesting: Having a Contribution and Owning It Are Different
Even when an employer does contribute, you may not keep all of it if you leave early. Your own deferrals are always 100% yours immediately. Employer contributions follow separate vesting rules depending on the plan type.
For discretionary employer contributions in a traditional 401(k), federal law allows two vesting schedules:10Office of the Law Revision Counsel. 26 USC 411 – Minimum Vesting Standards
- Cliff vesting: you own 0% of employer contributions until three years of service, then jump straight to 100%. Leave at two years and eleven months and you forfeit all of it.
- Graded vesting: 20% after two years, 40% after three, 60% after four, 80% after five, and 100% after six.
Safe Harbor contributions are the exception. Whether the employer uses the basic match, enhanced match, or non-elective formula, those contributions are 100% vested immediately. The same is true for SIMPLE IRA employer contributions.
Top-heavy minimum contributions follow whichever vesting schedule the plan document specifies, as long as it is either the three-year cliff or the two-to-six-year graded schedule. If your employer makes discretionary contributions and you are thinking about a job change, check your vesting percentage first. A few more months of service can be worth real money.
How to Tell Which Rules Apply to Your Plan
Pull your Summary Plan Description and look for three things. First, the plan type: a traditional 401(k), a Safe Harbor 401(k), or a SIMPLE IRA. Second, the contribution formula: whether it is described as discretionary or as a committed match or non-elective amount. Third, the vesting schedule for employer contributions. Those three items decide whether anything is owed to your account, how much, and when it becomes yours to keep.
If your plan is a traditional 401(k) with a discretionary match, your employer is within its rights to contribute less this year than last, or nothing at all. If it is a Safe Harbor plan, a SIMPLE IRA, or has been declared top-heavy, the contribution is required by federal law, not goodwill.