Solo 401(k)
A 401(k) for self-employed people with no employees, allowing both employee and employer contributions.
A solo 401(k) is a retirement plan for a business owner with no employees (other than a spouse). Its advantage is that you contribute in two capacities — as the employee and as the employer — which allows much larger total contributions than an IRA, up to a combined annual limit.
Like other 401(k)s it offers traditional and often Roth options, and it can be a powerful tax-deferral tool for profitable self-employed people. The contribution math depends on your net self-employment earnings, so it pairs closely with self-employment tax and QBI planning.
This definition is general information to help you understand a term, not financial, tax, or legal advice. Figures that change year to year (limits, thresholds, rates) should be confirmed against current official sources. For guidance on your situation, a licensed fee-only fiduciary is the right next step.