Review employee eligibility, related employers, contribution costs, provider capability and reporting before an owner-only business adds staff.

November 24, 2025 · Financial Forte Staff

Historical article: prepared retrospectively using information available as of November 24, 2025.

Hiring an employee can be a positive sign for a business that began with only its owner. It also changes the questions surrounding an owner-only 401(k). The plan may have been simple to administer because there were no eligible common-law employees, not because the account's “solo” label permanently exempts it from workforce requirements.

Review the retirement plan before the hiring decision becomes a payroll event. Determine when the employee becomes eligible, whether related businesses affect the analysis and whether the provider can administer the resulting arrangement. The answer may be to retain and adapt the existing plan, move to a provider that supports employees or choose a different design.[1][2]

Check eligibility using the actual plan and service

Read the signed plan document and adoption agreement. The employer may have chosen eligibility terms more generous than the maximum exclusions permitted by law. A general description of a one-year waiting period does not override a plan that offers earlier participation.

Hours and service history matter, including long-term, part-time rules. For applicable 401(k) plans, the enacted rules beginning in 2025 can require elective-deferral eligibility after two consecutive years with at least 500 hours, subject to age and other requirements. The ordinary service rules can create eligibility sooner. Do not treat “part-time” as a permanent exclusion.[3]

A new hire's earlier work for the business or a related employer may also need review. So may the status of someone previously treated as an independent contractor. Employment classification is a separate legal determination, not a label chosen to keep a retirement plan owner-only.

Prepare the employee's start date, expected hours, compensation, age and relevant prior service. Ask the administrator for a written entry-date determination. That date should reach payroll before deductions or employer contributions are due, rather than being discovered at year-end.

Include related businesses in the review

A sole owner may also have interests in another company, and a spouse or family member may own a related business. Controlled-group and affiliated-service-group rules can require a broader employer analysis for specified retirement-plan purposes. Separate EINs do not resolve that question.[2]

Owner-only treatment and ERISA coverage also depend on who participates and the applicable legal framework. The DOL's owner-only rules distinguish arrangements covering only qualifying owners and spouses from plans covering employees. Once the arrangement changes, oversight, disclosures and reporting need to be reviewed accordingly.[1]

Do not assume that the existing custodian's account paperwork covers every new obligation. Some providers support only one-participant arrangements. Ask whether the document and service agreement can accommodate employees, testing, notices and the required reporting, and identify any work that belongs to another administrator.

Compare employer costs before promising a contribution

Suppose an incorporated business has an owner earning $200,000 of eligible compensation and a new employee earning $60,000. Assume the employee is eligible for the full compensation period used in this illustration and all amounts satisfy the applicable compensation definition.

The owner has been considering an employer contribution equal to 20% of eligible pay. If a reviewed design applies that uniform percentage to both people, the owner allocation would be $40,000 and the employee allocation $12,000. The total employer contribution would be $52,000 ($40,000 for the owner plus $12,000 for the employee) before administration and other costs.

The extra $12,000 is part of the employee benefit budget. It should be considered alongside wages, payroll taxes and other costs of hiring. A business that budgets only the employee's salary can underestimate the commitment created by its intended retirement contribution.

For comparison, a hypothetical uniform 3% employer contribution on the same $260,000 compensation base would total $7,800: $6,000 for the owner and $1,800 for the employee. That changes the benefit for both people. It is not an instruction to replace an existing commitment or a conclusion that this design satisfies every applicable requirement.[4]

Other allocations or matching designs may be available, but the administrator needs the complete facts to evaluate limits, coverage and nondiscrimination. An owner cannot simply preserve a preferred personal allocation and assume the employee receives nothing because the account was originally opened as a solo plan.

Update the administration as well as the design

For an ERISA-covered plan, selecting and monitoring providers and investments and administering the plan can involve fiduciary duties. Document who handles eligibility, contributions, testing and participant communications. Keep a process for timely deposits and reconciliation rather than relying only on an annual tax appointment.[5]

Review reporting with the administrator. A one-participant plan's Form 5500-EZ rules and asset exception should not be carried forward automatically after employees participate. Confirm the reporting change before the one-participant filing is prepared. The correct annual filing category and any related requirements depend on the resulting plan, not the account nickname.[6]

Also review whether automatic enrollment or other newer requirements apply based on the plan's history and available exceptions. Adapting an older plan and establishing a new one may raise different questions. Obtain the determination before making enrollment statements to employees.[7]

The employee should receive a clear explanation of when participation begins, how to make an election and what the employer contribution requires. Confirm the first affected payroll and the corresponding account deposit, including any employee election to contribute nothing. Those simple checks can prevent a small eligibility misunderstanding from becoming an expensive correction.

Before the first hire, bring the plan documents, ownership information and proposed compensation to the benefits team. A plan that grows with the business can help attract and retain employees, but only if the business understands the cost and can administer the promised benefit consistently.

Related reading

Have more questions about solo 401(k) transitions and employee retirement benefits? Email Dave at dave@financialforte.com to discuss your questions and next steps.

The contact invitation is current; it does not imply this contact path existed on the historical reference date.

Educational information, not personalized investment, tax, legal or benefits advice. Examples use hypothetical assumptions. Verify current rules and your circumstances before acting.

Sources

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