Solo 401(k) Contributions Calculator: Maximizing Your Small Business Retirement Savings

Whether you’re a sole proprietor or run an S-corp, your business structure plays a crucial role in how much you can contribute to a solo 401(k).

• Sole proprietors or single-member LLCs’ contributions are calculated from net self-employment income (after expenses and half of your self-employment tax).
• S-corp and C-corp owners’ contributions are based on their W-2 salary.

Additionally, what makes a solo plan even more beneficial for business owners is that you contribute as both an employer and employee and bulk up your 401(k) even faster.

It goes without saying that if you make more, you can save more–but there actually is a cap on how much you can put away. According to IRS rules, you can’t exceed $69,000 in contributions, or $76,500 if you’re eligible for catch-up contributions.

Depending on your age, you can have a little more room to save more in your solo 401(k). Once you’re 50+, you can take advantage of catch-up contributions, which means if you have a solo plan, you can:

• Contribute an additional $7,500 in 2025
• Raise your employee contribution limit to $30,500 overall

Keep in mind that this applies to your employee portion only–not the employer side. Even if you’re not close to 50 yet, understanding how your contribution limits will change can help you maximize every savings opportunity that comes your way.

When exploring the different types of retirement plans, you’ll likely run into the SEP IRA and SIMPLE IRA along with the solo 401(k). While all three are designed for small businesses or self-employed use, they vary in offerings, and only a solo 401(k) can provide the full range of benefits necessary for self-employed individuals to keep their companies running smoothly:

What can you expect with a solo 401(k)?

• Employer and employee contributions
• Higher contribution limits
• Hardship loan options
• Roth and pre-tax options
• Catch-up contributions if you’re 50+
• More flexibility and hands-on management

What can you expect with a SEP IRA?

• No employee deferrals – only employer contributions
• Contribution limit up to 25% of income
• Less flexibility, even with simple setup
• No catch-up contributions
• No Roth or hardship loans allowed
• Works with any business, even if you have employees

What can you expect with a SIMPLE IRA?

• Lower contribution limits
• No Roth or hardship loans allowed
• Mandatory match
• Eligible to work with businesses with 100 or less employees

At Ubiquity, we believe retirement plans should be simple, affordable, and built around your business. No matter where you are in your retirement journey, we can set you up with a flat-fee solo 401(k) plan that provides the resources you need to grow your savings.