Those who are self-employed enjoy plenty of freedom in their work life and also plenty of risk. They can make up the rules for their workplace, but also must be responsible for benefits other workers are offered by their companies, including their retirement plans.

TheSelfEmployed.com noted that Social Security pays about $1,153 per month on average so a healthy nest egg will be needed to cover extra expenses. That is where a strong retirement plan comes in.

Here are the four top retirement plans for those who are self-employed, according to Forbes. They include a SEP-IRA, a simple IRA, a solo 401(k), and Keogh plans.

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Forbes recommended a SEP-IRA as its top choice for self-employed people. SEP stands for simplified employee pension. This IRA is a simple way to put money aside, pre-tax, as savings, the magazine noted. Under this IRA, investors can contribute as much as 25 percent of their income — up to $49,000 annually.

A simple IRA is just that — a simple incentive-match plan for employees at small businesses as well as the self-employed, Forbes reported. A solo 401(k) allows small business owners or those who are independently employed to contribute up to $16,500 annually, Forbes reported.

There are two types of Keogh plans — defined contribution and defined benefit. They are popular for those who are self-employed and earn large incomes, CNN noted. Under a defined benefit plan, you must fund it yourself. Under a defined contribution plan, you have two options — profit-sharing and money-purchase, CNN said.

Someone need not be a full-time business owner to use a retirement plan for the self-employed, according to financial adviser Jonathan Pond.

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"If you moonlight or just work part time, self-employed retirement plans offer great tax benefits," he wrote. "In fact, if you can spare the money, you may be able to put 100 percent of your net profit from self-employment into a plan and deduct it as well."

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