Coordinate employee deferrals across jobs while evaluating a separate employer contribution. Check compensation, related employers and business cash.

January 20, 2025 · Financial Forte Staff

Historical article: prepared retrospectively using information available as of January 20, 2025.

A profitable side business can create another opportunity to fund retirement. It does not automatically give the owner another personal employee-deferral limit. Confusing those two ideas can lead to excess contributions, while assuming the opposite can cause an owner to overlook a legitimate employer contribution.

Separate the employee and employer roles in each plan. Coordinate personal deferrals across the relevant arrangements, calculate the side business's contribution from the correct compensation and review whether the employers must be treated as related. The plan label alone does not settle those questions.

One person can participate through more than one employer

For 2025, the basic personal elective-deferral limit applicable to 401(k) and 403(b) participation is $23,500. Eligible catch-ups can add room under the applicable rules, but opening a second 401(k) does not duplicate the personal limit. Pre-tax and designated Roth deferrals count together for that purpose.[1][2]

Employer contributions follow a different calculation. A business may be able to contribute even when the owner has used the personal deferral limit elsewhere, subject to compensation, plan terms, deduction rules and annual-addition limits. The 2025 defined-contribution annual-addition dollar limit is $70,000, excluding eligible catch-up contributions, and the compensation limitation also applies.[1][2]

Do not simply subtract one employer's contribution from $70,000 and assume the remainder is available at every other business. Related-employer aggregation can change the analysis. Special coordination can also matter when a person participates in a 403(b) and controls another business. Governmental 457(b) arrangements follow a different personal-limit framework.[2][3]

Ask the administrator to map the actual employers, ownership and plan types before calculating available room. Provide ownership interests and family relationships for the professional review. A separate tax identification number is not proof that two businesses are unrelated for retirement-plan purposes.

Follow the dollars through a two-job example

In this hypothetical example, Casey, age 45, works for an unrelated employer and also operates an S corporation with no eligible employees other than Casey. Assume the ownership and plan review supports separate employer treatment and that all compensation and plan requirements are satisfied.

Casey elects $20,000 into the day-job 401(k) for 2025. That leaves $3,500 of the $23,500 basic personal deferral limit for the side-business 401(k). Electing another $23,500 from the side business would exceed the shared limit under these facts.

The S corporation pays Casey $60,000 of eligible W-2 compensation. Assume its plan permits a 25% employer contribution and the tax and plan limits allow the amount. The illustrative employer contribution is $15,000. Adding Casey's $3,500 employee deferral produces $18,500 in the side-business plan.

The $15,000 employer contribution does not consume the remaining $3,500 of personal elective-deferral room. It belongs to a different limit calculation. Likewise, the employer contribution is not based on Casey's total income from both jobs; it must be supported by the sponsoring business and the applicable compensation definition.

If Casey instead contributes the full $23,500 through the day job, no basic employee-deferral room remains for the side-business 401(k). The assumed $15,000 employer contribution could still be considered under the separate requirements. The change affects the employee portion, not automatically every contribution the business might make.

Use the right compensation and cash source

An S corporation owner's distributions are not interchangeable with W-2 wages for this calculation. A sole proprietor or partner follows self-employed earned-income rules, including adjustments that make a simple percentage of gross revenue inappropriate. The familiar 25% employee-compensation formula should not be copied onto unadjusted Schedule C profit.[2]

Have the tax professional and administrator agree on the compensation input and contribution calculation. Keep the worksheet with the plan records. A contribution estimate made before the books close may need revision when income and deductions are finalized.

For Casey, the $15,000 employer contribution also requires actual business cash. If the company has $25,000 available but needs $18,000 for operating commitments, only $7,000 remains before considering other obligations. That is $8,000 less than the illustrated $15,000 employer contribution. A deductible contribution is not automatically affordable merely because the tax calculation permits it.

Compare the desired funding with the business's reserve, taxes and upcoming expenses. If the contribution must be reduced, determine the permitted amount and any commitments created by the plan. Do not promise a discretionary contribution as though every plan design allows unrestricted annual changes.

Hiring employees can also change the arrangement. Review eligibility and the full workforce before assuming an owner-only plan can continue excluding everyone else. Related businesses and employee service can matter even when the owner thinks of the venture as a small side project.[2]

Make coordination an annual operating task

Create a contribution inventory showing each employer, plan type, employee deferrals, employer contributions and tax treatment. Update it after a job change, bonus or revised election. Check the combined totals before the final payroll elections for the year and ask both administrators how to address a potential excess promptly rather than waiting until the return is being filed.

Owner-only arrangements can be outside ERISA Title I when the applicable conditions are met, but tax qualification, records and reporting still need attention. If common-law employees participate, review the additional obligations and applicable fiduciary responsibilities. “Solo” is not a permanent exemption from administration.[4]

Assign responsibility for the calculation and confirmation of deposits. For a business owner, this can reduce correction risk and improve the accuracy of both retirement funding and cash forecasts. It also makes the transition to an employee plan easier if the business grows.

Start with all of your contributions, not just the side-business account. Coordinating the personal limit with the business's separate contribution rules can reveal useful savings room without relying on an assumption that each new plan creates a new personal maximum.

Related reading

Have more questions about side-business retirement plans and contribution coordination? 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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