How Do Individual 401 (k) Plans Work?

Choosing the right retirement plan is an important step in shaping your financial future. If you want more control over your investments, several individual options can support long-term growth and security, but a self-directed Individual 401(k), or a Solo 401(k), is often a wise choice.

Individual 401(k)s offer high contribution limits and are available for business owners with no employees. When self-directed, these plans are powerful tools to invest retirement funds in high-growth assets like real estate while also lowering your taxes.

For many business owners, this unique investment vehicle is the most effective way to build a strong retirement foundation, but is it right for you? We’ll go through six key points to help you understand what sets it apart from other accounts and whether it’s the best path for you.

What is an Individual 401 (k) Plan?

Individual or Solo 401(k) plans are designed for business owners with no employees. If you’re self-employed—either part-time or full-time—you can open an account for yourself. You can also cover a spouse.

Because you act as both the employer and the employee, you’re able to contribute in both roles, which helps amplify your savings.

As the account holder, you can split contributions between different sub-accounts, borrow against your balance, and benefit from tax advantages built into 401(k) accounts. When properly structured, you can also invest in alternative assets, such as real estate, private equity, and cryptocurrency.

Contribution Limits

High contribution limits and the ability to contribute two different ways make Individual 401(k)s incredibly popular retirement plans for self-employed individuals.

The 2026 maximum contribution limits for 401(k) are as follows:

• Employee contribution limit. $24,500 (up from $23,500 in 2025)
• Catch-up contribution limit (age 50+). An additional $8,000, bringing the total employee limit to $32,500 for qualified plan holders (up from $7,500 in 2025).
• Enhanced catch-up (ages 60 to 63). If your plan allows, you may contribute up to $11,250 during this age window.

Total combined limit. When you add both employee and employer contributions, you can contribute up to $72,000 in 2026.

These expanded limits make Individual 401(k) plans, especially self-directed plans, among the most powerful tools for growing retirement savings, allowing business owners to maximize both tax advantages and investment flexibility.

Tip: Contribution limits can and often do change annually. Always check with your custodian or the latest IRS guidance for the most up-to-date information.

Individual 401(k) qualifications?

To open an individual 401(k), you must meet the following requirements:

• Earn self-employed income, either full-time or from a part-time side business.
• Operate under an eligible business structure, such as a sole proprietorship, LLC, partnership, C-corporation, or S-corporation.
• Have no full-time employees, with the exception of a spouse or business partner.

Meeting these qualifications allows you to take advantage of the tax benefits and flexible contribution rules of an individual 401(k).

What are The Different Types?

There are two primary ways an individual 401(k) can be structured, each with unique tax advantages:

Traditional individual 401(k)

• Contributions are made with pre-tax dollars.
• Funds grow tax-deferred
• Withdrawals in retirement are taxed as ordinary income.

Roth individual 401(k)

• Contributions are made with after-tax dollars.
• Funds grow tax-free
• Qualified withdrawals are tax-free.
• Withdrawals from contributions are tax-free.

Brokerage accounts vs. fully self-directed accounts

Individual 401(k) plans can be structured in two ways, and the difference comes down to investment flexibility.

Brokerage-based solo 401(k)s, often offered by major financial institutions, limit you to traditional assets such as stocks, bonds, ETFs, and mutual funds. They are easy to manage, but asset control is limited, and you cannot hold alternative investments.

A fully self-directed individual 401(k) offers a much wider range of IRS-approved assets, including real estate, private equity, precious metals, and promissory notes.

Specialized custodians, like Horizon Trust, typically offer these plans and allow you to maintain checkbook control. This feature will enable you to make investments directly from the plan without waiting for custodian approval. This structure is ideal for business owners who want greater control, faster transactions, and broader diversification in their retirement strategy.

Selecting the retirement plan for you

Choosing the right retirement plan starts with understanding your business structure, income level, and long-term goals.

As you compare plans, consider factors such as:

• How much you want to contribute each year
• Whether a traditional or Roth structure better supports your tax strategy
• Whether you want access to alternative assets, and
• How hands-on you want to be with managing investments

If you’re a small business owner or self-employed professional, you still have access to robust retirement options that can help you build long-term security. Reviewing these choices with a financial advisor can help you select the structure that aligns with your goals.

FAQs

Who is eligible to open a self-directed individual 401(k)?

You must have self-employment income and no full-time employees other than a spouse or business partner. Eligible business structures include sole proprietorships, LLCs, partnerships, S-corps, and C-corps.

Can I have an individual 401(k) if I already work a W-2 job?

Yes. If you earn self-employment income from a side business, you may still open an individual 401(k). However, employee contribution limits are shared across all 401(k) plans you participate in.

What makes a self-directed individual 401(k) different from a brokerage solo 401(k)?

A self-directed individual 401(k) allows investment in alternative assets like real estate, private equity, precious metals, and promissory notes, while brokerage solo 401(k)s typically limit you to stocks, ETFs, and mutual funds.

Can I invest in real estate or crypto with a self-directed individual 401(k)?

Yes, when properly structured, a self-directed individual 401(k) can invest in IRS-approved alternative assets, including real estate and cryptocurrency, as long as prohibited transaction rules are followed.

What is checkbook control, and why does it matter?

Checkbook control allows you to make investments directly from your individual 401(k) without waiting for custodian approval, enabling faster execution and greater control over investment decisions.

Are loans allowed from a self-directed individual 401(k)?

Yes. Individual 401(k) plans allow participant loans of up to 50% of the account balance or $50,000 (whichever is less), provided the plan document permits loans and repayment rules are followed.

Can I choose both Traditional and Roth contributions in the same plan?

Yes. Many individual 401(k) plans allow both Traditional (pre-tax) and Roth (after-tax) contributions, giving you flexibility to balance current tax savings with tax-free retirement income.

Do self-directed individual 401(k)s have required minimum distributions (RMDs)?

Traditional individual 401(k)s are subject to RMDs starting at the applicable IRS age.