Most entrepreneurs are concerned not only with growing their business but with effectively funding and securing their retirement. Until recently, business owners could only choose from a short list of options, namely a SIMPLE IRA, SEP -- IRA, and Keogh. Enter the Solo 401(k) plan. It doesn't matter what type of business you own or if you have any employees, you can establish a Solo 401(k). They are easy to set up; unlike larger company 401(k) plans, there are no complicated administrative requirements. Once you establish your 401(k), you can roll over other retirement accounts into it. As of 2006, total annual contributions to a Solo 401(k) can be up to $44,000 or 100% of compensation. Business owners 50 years or older can take advantage of a catch -- up provision that allows an additional $5,000 contribution. Couples can contribute up to $98,000. The contributions to your Solo 401(k) are based on self -- employment income, not on income earned. While most retirement plans provide a tax break and help you save for the future, the self -- employed 401(k) offers additional benefits: Contribution flexibility -- Since it's viewed as a 401(k) with profit sharing, you get to decide each year whether to contribute and how much to contribute to your Solo 401(k). Meaning, if you have a good year, you can choose to put more money into your plan, but if your earnings are less than favorable, you can choose to put little or nothing at all into your plan, says Craig Lewis Gillooly, CEO of www.401kbrokers.com. Higher contribution limits -- You can contribute more money to a Solo 401(k) on less income than you can to an IRA, Simple IRA, or a SEP -- IRA. For example, a SEP allows only employer contributions, which are generally limited to 25% of compensation to a maximum of $44,000 as of 2006. With a Solo 401(k), employer contributions are limited to 25% of compensation, but there is an additional "employee" contribution that can be made -- $15,000 or 100% of income, explains Gillooly. Access to cash -- You can get a loan of up to $50,000 or no more than 50% of your Solo 401(k) account balance. The money can be used for any purpose and is tax and penalty free as long as it is paid back on time (generally five years; longer if the loan is used to acquire a principal residence). You cannot borrow from a SEP -- IRA or IRA, although you can rollover assets from such retirement plans into a Solo 401(k) and borrow from them. There are a number of firms that now offer Solo 401(k) plans, including AIM Investments, A.G. Edwards, T. Rowe Price, Wachovia Securities, Charles Schwab, Fidelity Investments, and ING Financial Partners. For a comprehensive list, check out www.401khelpcenter.com. When sizing up what various firms offer in terms of Solo 401(k) plan services, here's what to look for: Low expense ratios -- You want to look at costs like the internal expense ratio of the investment fund options, says Rick Meigs, president of 401khelpcenter.com L.L.C. Expense ratios vary widely and directly impact your return. You can look up expense ratios for any fund at www.morningstar.com. No or low setup costs and annual fees -- You want ease and simplicity of account setup and ongoing maintenance, says Meigs. Compare the load fees and administrative fees of one or more Solo 401(k) plans to make sure you aren't paying too much . Investment flexibility -- Find out if you are restricted to a limited number of funds or if the "platform" is open, allowing you to invest in stocks, bonds, mutual funds, and real estate, advises Meigs. Can you use low -- cost index funds, which tend to have lower expense ratios? Will the firm selected take care of any regulatory filings (for example Form 5500 may be required) and all compliance issues? Does it provide good telephone and/or e -- mail support?