Establishing a Small-Business 401(k) Plan

Adapted from 401(k) Plans For Small Businesses, published by the U.S. Department of Labor; selected section: Establishing a 401(k) Plan. The source text is reproduced with headings and formatting adjusted for this guide.

Establishing a 401(k) Plan

When you establish a 401(k) plan, you must take certain basic actions. One of your first decisions will be whether to set up the plan yourself or to consult a professional or financial institution – such as a bank, mutual fund provider, or insurance company – to help you establish and maintain the plan. In addition, there are four initial steps for setting up a 401(k) plan:

• Adopt a written plan document,
• Arrange a trust for the plan's assets,
• Develop a recordkeeping system, and
• Provide plan information to eligible employees.

Adopt a written plan document – Plans begin with a written document that serves as the foundation for day-to-day plan operations. If you hired someone to help with your plan, they will likely provide the document. If not, consider getting assistance from a financial institution or retirement plan professional. In either case, you will be bound by the terms of the plan document.

Once you have decided on a 401(k) plan, you will need to choose the type of plan best for you – a traditional 401(k) plan, a safe harbor 401(k) plan, or an automatic enrollment 401(k) plan. In all the plans, participants can contribute through salary deductions.

A traditional 401(k) plan offers the most flexibility. Employers can decide whether to contribute for all participants, to match employees' deferrals, to do both, or to do neither. These contributions can be subject to a vesting schedule, which means an employee only has a right to employer contributions after a certain amount of time. Annual testing ensures that benefits for rank-and-file employees are proportional to benefits for owners/managers.

Safe harbor 401(k) plans are not subject to the annual contributions testing that traditional 401(k) plans require. In exchange for avoiding annual testing, employees in these plans must receive a certain level of employer contributions. Under the most popular safe harbor 401(k) plan, employees are immediately vested in employer contributions.

An automatic enrollment 401(k) plan allows you to automatically enroll employees and place their salary deductions in certain default investments unless the employee elects otherwise. This is an effective way for employers to increase participation in their 401(k) plans.

The traditional, safe harbor, and automatic enrollment plans are for employers of any size.

This booklet addresses traditional and safe harbor 401(k) plans. For more information on automatic enrollment 401(k) plans, see Automatic Enrollment 401(k) Plans for Small Businesses (Publication 4674).

Once you have decided on the type of plan for your company, you have flexibility in choosing some of the plan's features, such as which employees can contribute to the plan and how much. Other features are required by law. For instance, the plan document must describe certain key processes, such as how contributions are deposited in the plan.

Arrange a trust for the plan's assets – A plan's assets must be held in trust to assure that the assets are used solely to benefit the participants and their beneficiaries. The trust must have at least one trustee to handle contributions, plan investments, and distributions. Because the financial integrity of the plan depends on the trustee, selecting a trustee is one of the most important decisions you will make in establishing a 401(k) plan. If you set up your plan through insurance contracts, the contracts do not need to be held in trust.

Develop a recordkeeping system – An accurate recordkeeping system will track and properly attribute contributions, earnings, losses, plan investments, expenses, and benefit distributions. If a contract administrator or financial institution assists in managing the plan, that entity typically will help keep the required records. In addition, a recordkeeping system will help you, your plan administrator, or your financial provider prepare the plan's annual return/report that must be filed with the Federal Government.

Provide plan information to employees eligible to participate – You must notify employees who are eligible to participate in the plan about certain benefits, rights, and features.

In addition, a summary plan description (SPD) must be provided to all participants. The SPD is the primary way to inform participants and beneficiaries about the plan and how it operates. It typically is created with the plan document. (For more information on the required contents of the SPD, see Disclosing Plan Information to Participants.)

You also may want to provide your employees with information that discusses the advantages of your 401(k) plan. The benefits to employees – such as pretax contributions to a 401(k) plan (or tax-free distributions in the case of Roth contributions), employer contributions (if you choose to make them), and compounded tax-deferred earnings – help highlight the advantages of participating in the plan.

A 401(k) plan may be established as late as the due date (including extensions) of the company's income tax return for the year you want to establish the plan.

For example, if your business's fiscal year ends on December 31, 2026, and you filed for the automatic 6-month extension, the company's tax return would be due on October 15, 2027. You could adopt a plan in 2027 as late as October 15 and make it effective on December 31, 2026. You're not allowed to have 401(k) salary deferrals prior to the date you adopt a 401(k) plan. However, you could make an initial profit sharing contribution to the 401(k) plan for 2026, no later than October 15, 2027.

This guide concerns U.S. workplace benefits and the federal rules described by the Department of Labor. The type of plan, its governing documents, and the facts of a claim matter. Government, church, and other excluded plans may follow different rules.

Source and scope

401(k) Plans For Small Businesses — U.S. Department of Labor. Accessed October 28, 2026. This public domain federal guidance is an educational reference; use the source publication and the applicable plan or employment documents for the full context and later updates. Fynoptic is independent and is not endorsed by the Department of Labor.