Retirement Plan Tax Rules, Part 1
If you are a self-employed individual with employees, you may want to consider establishing a SEP, which does not need IRS approval. Under SEP, you may contribute, for yourself and your employees, to a special type of IRA--more than is allowed under the regular IRA rules. As the business owner, your annual contributions to your SEP account may not exceed 20 percent of your net earnings (25 percent of your employee's compensation) or $40,000 ($41,000 for individuals age 50 or older), whichever is less. The deadline for both setting up and contributing to a SEP is the due date for your Form 1040 individual tax return (including extensions).
Source: "Selecting the Right Retirement Plan"