Simple definition
A Solo 401(k) is a retirement plan for self-employed people who have no employees other than a spouse. Because you're both the boss and the worker, you can contribute in two roles — as an employee from your earnings and as the employer from your business. Think of wearing two hats and putting money in from each. That dual contribution lets solo business owners save substantially more than many other plans allow.
Why it matters
For freelancers and one-person businesses, a Solo 401(k) offers one of the highest contribution ceilings available, plus a possible Roth option. It lets self-employed people build serious retirement savings and cut taxable income in strong-earning years, filling a gap regular jobs handle through workplace plans.
Real-life example
You freelance and net $80,000. As the 'employee' you contribute from your pay, and as the 'employer' you add a percentage of business profit, letting you sock away far more than a standard IRA would permit that year.
Common mistakes
- Assuming you can use one if you have full-time employees — you generally can't.
- Missing the plan setup deadline, which can cost you a year of contributions.
- Overlooking the higher combined limit by only contributing as the employee.
- Ignoring required paperwork once the account balance grows large.
Pro tips
- Confirm you have no eligible employees besides a spouse before opening one.
- Contribute in both roles to reach the higher combined limit.
- Check contribution limits, which the IRS sets and adjusts annually.
- Consider a Roth Solo 401(k) option if you expect higher taxes later.
Related Money Dictionary terms
- SEP-IRAA retirement plan for self-employed people and small business owners that allows larger contributions than a standard IRA.
- SIMPLE IRAA retirement plan for small businesses that lets both employees and the employer contribute with less paperwork than a 401k.
- 401(k)A retirement account through your job, often with an employer match — free money for saving.
- Contribution LimitThe maximum amount the government lets you put into a retirement account in a single year.
- Self-Employment TaxThe Social Security and Medicare tax that self-employed people pay to cover both the employee and employer shares.
- Roth 401(k)A workplace retirement account where you contribute after-tax money so qualified withdrawals in retirement come out tax-free.
Frequently asked questions
Who qualifies for a Solo 401(k)?
Self-employed people and business owners with no employees other than a spouse. That includes freelancers, consultants, and sole proprietors. If you hire full-time employees who meet eligibility rules, you generally can no longer use a Solo 401(k) and must consider a different plan for the business.
How much can I contribute?
Because you contribute as both employee and employer, the combined ceiling is high — among the largest for self-employed plans. The exact limits are set by the IRS and adjusted annually, with a catch-up amount for those 50 and older. Check current figures on IRS.gov before you contribute.
Solo 401(k) or SEP IRA?
Both suit the self-employed, but a Solo 401(k) often allows larger contributions at moderate income because of the employee portion, and may offer a Roth option and loans. A SEP IRA is simpler with less paperwork. The right choice depends on your income, savings goal, and how much complexity you'll accept.
Knowing what Solo 401(k) means is knowledge — the first half. A brick gets placed when you act on it: confirm you have no eligible employees, then price out opening a Solo 401(k).
Sources & references
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Plain-English education — not personalized legal, tax, or investment advice.