If you are self-employed, retirement may be a scary thought. After all, you don't have a 401(k) or pension to rely on to provide you with a nest egg once you reach retirement age, and an IRA alone might not be enough.

Fortunately, there are special accounts designed specifically for self-employed individuals and small-business owners to save for retirement in the same tax-deferred way that corporate employees have access to. Here is a brief overview of the options available, so you can decide which is right for you.

SIMPLE IRA
The term SIMPLE IRA stands for Savings Incentive Match Plan for Employees. As the name implies, it's a pretty straightforward option. This account type is available to small businesses with fewer than 100 employees, and includes the self-employed -- you are considered a small business of one employee.

Under the IRS rules for SIMPLE IRA accounts, the employee is allowed to contribute up to $12,500 in 2015 -- an extra $3,000 is allowed if over 50 -- and the employer is generally required to contribute up to 3% of the employee's salary on a matching basis (or 2% nonelective profit-sharing contribution), up to the compensation limit of $265,000. So, if you are self-employed, your maximum contribution is $12,500 plus 3% of your earnings (so, depending on your circumstances, up to $19,950). No other money can be contributed to a SIMPLE IRA.

It's also important to note that, if you participated in any other retirement plans throughout the year, like a former employer's 401(k), your total elective retirement contributions are limited to $18,000 in 2015, including contributions to the SIMPLE IRA.

Investment choices are the same as you would find in a traditional or Roth IRA. Account holders are free to invest in pretty much any stocks, bonds, or funds they choose.

SEP-IRA
A "Simplified Employee Pension," or SEP, is another IRA-like account, with all contributions coming from the employer -- you, if you're self-employed. And despite the fact that the other plan is called "simple," I would actually make the argument that the SEP is the easiest option for most self-employed people.

Unlike the SIMPLE IRA, the SEP version has a very straightforward contribution limit. As a self-employed individual, you can contribute up to 25% of your self-employment income up to a maximum of $53,000 in 2015.

There are no "catch-up" contributions for those account holders over age 50, and because all of the contributions to the SEP account technically come from the employer, there are no complicated employer/employee contribution rules. And just like the SIMPLE account, you can invest just like a traditional or Roth IRA – in any stock, bond, or fund you wish.

Individual 401(k)
These types of retirement accounts are also known as one-participant 401(k)s, or solo 401(k)s, and they have the same rules and requirements as other 401(k) plans. Unlike most employer-sponsored 401(k) plans, which limit your investments to a basket of funds, you can potentially use an individual 401(k) to invest in stocks, bonds, and CDs, as well.

Because you serve as both employer and employee, the contribution rules can get a little complicated. As the employee, you can elect to defer up to 100% of your income up to $18,000 in 2015 ($24,000 if over 50). And as the employer, you can contribute 25% of your "compensation," which the IRS defines as your net earnings minus your elective contributions and half of the self-employment tax.

Total contributions to a one-person 401(k), or any 401(k) for that matter, are capped at $53,000 for the 2015 tax year, not counting catch-up contributions. However, even though the cap is technically the same as a SEP account, because you can contribute 25% of your compensation plus up to $18,000 in elective deferrals, the individual 401(k) generally has the highest contribution limit for moderate-income individuals.

Which is best for you?
It depends. The SIMPLE and SEP-IRA accounts are definitely the easiest, and work just like an ordinary IRA. On the other hand, the 401(k) will usually allow you to set aside more money, and in some cases a lot more.

Regardless of which particular account type you choose, all three of these are excellent options for self-employed individuals looking to take their retirement planning to the next level.