Retirement Plans for Personal Trainers: Solo 401(k), Roth, and the Online Income Question

Personal trainers with no employees (other than a spouse) have access to the Solo 401(k), which allows contributions of up to $70,000 per year (2025). All sources of self-employment income count toward the contribution calculation: in-person training sessions, online coaching, program sales, class instruction, and supplement commissions. The Solo 401(k) is the most tax-efficient retirement vehicle for solo trainers because it combines the highest contribution limits with the lowest administrative burden.

How much can a personal trainer contribute?

What if the trainer hires an assistant or another trainer?

When the trainer hires an employee (a second trainer, an administrative assistant, a class instructor), the Solo 401(k) is no longer available. The business must transition to a plan that covers eligible employees:

• SIMPLE IRA: $16,500 deferral (2025; $17,600 for an employer with 25 or fewer employees) + 3% employer match. Lower owner contribution ceiling but lower employer cost.
• Safe Harbor 401(k): $23,500 deferral + 3% non-elective or 4% match for all eligible employees. Higher owner contribution but higher compliance cost ($1,500-$3,000/year TPA).

The Solo 401(k) can remain in place until the employee meets the plan’s eligibility requirements (typically 1 year of service and 1,000 hours). A part-time front desk person working 15 hours/week (780 hours/year) may never become eligible.

When is the deadline to set up and fund a retirement plan for tax purposes?

Setup and funding deadlines vary by plan type. A SEP-IRA can be established and funded up to the tax filing deadline including extensions (October 15, 2026 for a sole proprietor who extends a 2025 return; an S corporation follows its own return’s due date). A solo 401(k) doesn’t have to be established by December 31: a plan adopted by the filing deadline, including extensions, can be treated as in place for the prior year, and employer contributions can be made until that deadline. Employee deferrals in an existing plan must be elected by December 31 (an S corporation owner’s come out of paychecks, so the election has to be in before the last one of the year); a sole proprietor can then deposit them by the filing deadline including extensions. In a plan adopted after year-end, first-year deferrals are open only to an unincorporated owner who is the business’s only employee, and the plan and the deferrals must be in by the unextended due date (April 15, 2026 for 2025). A SIMPLE IRA must be established by October 1 of the tax year. A defined benefit or cash balance plan can also be adopted up to the filing deadline including extensions, and its minimum required contribution is due 8.5 months after the plan year ends.

Can a personal trainer open a Solo 401(k) after December 31?

Yes, if you train on your own as a sole proprietor with no employees. Under SECURE 2.0 you can adopt a Solo 401(k) after year-end and still make first-year employee deferrals, as long as they’re in by your unextended return date: April 15, 2026 for 2025. The employer contribution can wait until the extended due date, October 15, 2026 with Form 4868.

The option has limits. It doesn’t apply to a trainer who works through an S corporation, and it doesn’t apply once you have employees. After the first year, deferrals are elected by December 31 and can be deposited by the return deadline with extensions.

• For 2026 the deferral limit is $24,500, and trainers age 60 to 63 can add a catch-up of $11,250.

• A trainer who’s also a W-2 employee at a gym shares one deferral limit across both plans, since the limit is per person.

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This guide is general information, not tax advice for your specific situation. Which points apply, and how, depends on your facts.