If you are self-employed, you can set up and contribute to a SEP-IRA for yourself and your employees.

For your employees, the maximum contribution is 25 percent of wages or a certain dollar amount, whichever is less. This dollar amount is 44,000 for 2006 and $45,000 for 2007.

For yourself, the maximum contribution is 25 percent of net self-employment income, which is defined as your net business profit minus one-half of your self-employment (Social Security and Medicare) taxes minus your SEP-IRA contribution.

To figure out how much you can actually contribute, simply multiply your net business profit minus one-half of self-employment taxes by 20 percent (0.20).

If all of your income comes from self-employment, use Fidelity's SEP-IRA calculator to figure out your contribution limit. It will figure out your self-employment taxes for you.

If you have a job where you are contributing to your employer's retirement plan, you can still have a SEP-IRA if you have self-employment income from a free-lance or side job.

In this case, use the calculator from U.S. Global Investors at http://www.usfunds.com/tools/sep_contributions.asp because it will let you enter your self-employment taxes yourself.