A SIMPLE IRA (Savings Incentive Match Plan for Employees) is a retirement savings plan for small businesses (100 or fewer employees). It's easier and cheaper to administer than a 401(k). Employees can contribute pre-tax income, and employers must contribute, either matching employee contributions up to 3% of their compensation or making a fixed 2% contribution for all eligible employees, regardless of whether the employee contributes. Contributions grow tax-deferred, and withdrawals in retirement are taxed as ordinary income. There are penalties for early withdrawals before 59 1/2. It provides a straightforward way for small businesses to offer retirement benefits.

A SEP IRA (Simplified Employee Pension) is a retirement plan for self-employed individuals and small business owners. Unlike a SIMPLE IRA, only the employer makes contributions; employees cannot contribute. The employer can contribute up to 20% of net self-employment income or 25% of an employee's compensation (up to a certain limit, adjusted annually). Contributions are tax-deductible for the employer, grow tax-deferred, and are taxed as income upon withdrawal in retirement. It's a relatively simple and flexible plan, requiring minimal paperwork and administration compared to other employer-sponsored plans. SEPs are a good option for solo entrepreneurs and small businesses.

A Solo 401(k) is a retirement plan for self-employed individuals and business owners with no full-time employees (except a spouse). It allows contributions as both "employee" and "employer," enabling significantly higher contributions than many other plans. As the employee, you can make elective deferrals (traditional or Roth). As the employer, you can contribute up to 20% of net self-employment income or 25% if incorporated. Combined contributions have an annual limit. The Solo 401(k) offers tax-deferred growth (or tax-free for Roth), potentially higher contribution limits, and some plans allow for loans. It is good for solopreneurs.

A Safe Harbor 401(k) is a type of 401(k) plan that automatically satisfies certain IRS nondiscrimination testing requirements. This testing ensures plans don't disproportionately benefit highly compensated employees. To qualify, employers must make specific contributions to employees' accounts. These can be either a non-elective contribution (e.g., 3% of compensation for all eligible employees, regardless of participation) or a matching contribution (e.g., 100% match on the first 3% deferred, plus 50% on the next 2%). Safe Harbor contributions are immediately 100% vested. This simplifies administration and provides a guaranteed benefit for employees, making it a popular choice.

A small business 401(k) is a retirement savings plan offered by small companies to their employees. Like larger company 401(k)s, it allows employees to contribute a portion of their pre-tax salary, often with an employer matching contribution. These plans offer tax advantages, helping employees save for retirement while potentially reducing the employer's tax liability. Administration can range from simple to more complex, generally it is more involved than the IRA based plans. It is an important benefit for attracting and retaining employees.

A New Comparability plan is a type of profit-sharing plan, often combined with a 401(k), that allows for different contribution rates for different groups of employees. While seemingly discriminatory, it passes IRS nondiscrimination testing by demonstrating that the benefits provided are comparable across groups, when future projected values are examined. This allows a small business to provide significantly larger contributions to certain groups, often owners and key employees, than to others, while staying within legal limits. The complex calculations requires specialized administration and is most suitable for businesses wanting to maximize contributions for specific employees while still providing a benefit to all.