Here's how three common retirement savings plans for self-employed workers stack up based on contribution limits, costs and more. Getty Images By Mary Kane, Associate Editor February 21, 2018From Kiplinger's Retirement Report Whether you're a full-fledged small-business owner or you just run a business on the side, there are several smart ways to save for retirement that are specifically designed for the self-employed. Here's a comparison of three popular self-employed retirement savings plans: the solo 401(k), the SEP IRA and a SIMPLE IRA. See which option is right for your retirement planning needs.SEE ALSO: Retirement Savings Plans for the Self-Employed Solo 401(k) Works well for: A self-employed business owner with no employees or a worker participating in an employer’s 401(k) who also has a side business. How much you can contribute: As an employee, you can contribute up to $18,500 for 2018, plus up to $6,000 extra if you are 50 or older. As a sole proprietor, you can contribute 20% of your company’s net earnings. For 2018, total contributions can’t exceed $55,000 (not counting the catch-up contribution). Maximize it: If you have a side gig and work for a company with a retirement plan, contribute to both. How much it costs: There’s usually no annual maintenance fee, but you’ll need to file an annual IRS Form 5500 if your plan assets exceed $250,000. Advertisement SIMPLE IRA Works well for: Self-employed people with fluctuating incomes (such as real estate agents) or a business with 100 or fewer employees. Both employer and employee can contribute. How much you can contribute: Up to $12,500 in salary deferrals, or $15,500 if 50 or older. Employers match employee contributions up to 3% of compensation, which can be reduced to 1% in any two out of five years. Or an employer can contribute 2% of each employee’s compensation, up to $5,500. Maximize it: Some firms start out with a SIMPLE IRA and then change to a 401(k) when they have more employees or want to match more than the 3% limit in a SIMPLE plan. How much it costs: Costs vary by plan provider. Fidelity, for example, charges an annual fee of $25 per participant, or a $350 plan fee. Advertisement SEP IRA Works well for: A small business with only a few employees or a self-employed owner who might have made a nice profit last year but needs more time to establish a plan. (You have until October 15, 2018, to set up a plan for 2017. Other plans must be set up by the end of the year for which contributions are made.) How much you can contribute: No employee contributions. You as the employer can contribute up to 20% of your net income, to a maximum of $55,000. Maximize it: Only the employer can contribute. Whatever percentage you select, you must contribute the same percentage of compensation for each employee. SEE ALSO: How the New Tax Law Affects Retirees and Retirement Planning How much it costs: There often is no setup or annual maintenance fee. Check with brokerage and mutual fund companies that sponsor SEPs.