Rules of 401(k) Plans

Written by True Tamplin, BSc, CEPF®

Reviewed by Subject Matter Experts

Updated on January 29, 2024

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What Are the Rules of 401(k) Plans?

A 401(k) plan is a retirement savings plan primarily sponsored by an employer. It allows employees to save and invest part of their paycheck before taxes are taken out.

The IRS sets the rules for 401(k) plans, determining contribution limits, distribution rules, and the eligibility criteria for tax benefits.

These rules also establish the responsibilities of plan fiduciaries and specify what investment options can be made available to plan participants.

The rules of 401(k) plans encompass various aspects such as eligibility criteria, contribution limits, vesting schedules, investment options, and the withdrawal rules.,

Additionally it covers the rules on required minimum distributions (RMDs), the tax implications, loan provisions, and penalties for early withdrawals.

Eligibility and Enrollment

To fully take advantage of a 401(k) plan, employees must meet certain eligibility requirements and complete an enrollment process.

Criteria for Eligibility

To participate in a 401(k) plan, employees must meet eligibility requirements, often set by the employer, but generally following the IRS guidelines.

These may include being of a certain age (usually 21) and having a minimum length of service.

Additionally, the plan might exclude certain types of employees, such as part-timers or union members, depending on the terms set forth in the plan document.

Process of Enrolling in a 401(k) Plan

Enrollment processes vary among companies. Some automatically enroll their employees, while others require employees to opt in. Often, enrollment involves deciding how much to contribute and choosing investment options.

This process is typically managed online, allowing employees to change their contribution amounts and investment choices at any time.


A key aspect of 401(k) plans is the contribution structure. This structure includes employee contributions and may involve employer contributions as well.

Employee Contributions

Employees can elect to defer a portion of their salary to their 401(k) plan. The contribution limit for 2024 is $23,000 per year for those under 50, and an additional $7,500 for those 50 or older.

These contributions are typically made pre-tax, but some plans offer a Roth option where contributions are made after-tax.

Employer Contributions

Many employers match their employees' contributions to a certain extent, effectively providing free money towards their employees' retirement savings. The matching structure can vary significantly between different employers.

For instance, an employer might match 100% of an employee's contributions up to 3% of their salary, or 50% of contributions up to 6% of their salary.

Total Employer And Employee Contributions

The maximum amount that both the employer and employee can contribute to all of the employer's plans is limited each year. This limit is determined by the lower of two options: either 100% of the employee's compensation or $69,000 for the year 2024.


Vesting refers to the ownership of funds in a 401(k) plan. It's a critical concept in understanding how 401(k) plans work.

Definition of Vesting

Vesting in a 401(k) plan indicates the percentage of employer contributions that an employee has the right to take with them if they leave the company.

An employee's own contributions are always 100% vested—that is, completely owned by the employee. However, employer contributions may be subject to a vesting schedule.

Types of Vesting Schedules

There are generally two types of vesting schedules: cliff and graded. Under a cliff vesting schedule, employees become fully vested after a certain period of service, commonly three years.

In contrast, under a graded vesting schedule, employees gradually earn rights to employer contributions over time, often becoming fully vested over a period of six years.

Investment Options

401(k) plans typically offer a variety of investment options. Understanding these choices and how to allocate assets is fundamental to maximizing potential returns.

Investment Choices

A 401(k) plan usually includes a range of investment options including mutual funds, index funds, and target-date funds.

Each fund has its own risk and return profile, and employees are responsible for choosing how to invest their contributions based on their individual risk tolerance and retirement goals.

Asset Allocation and Diversification

Asset allocation refers to the distribution of investments among different asset classes, such as stocks, bonds, and cash equivalents. Diversification is a strategy that spreads investments across various assets to reduce risk.

Balancing these two strategies can help 401(k) participants achieve their long-term financial goals while mitigating risk.

Withdrawals and Distributions

401(k) plans are designed for long-term retirement savings, and thus have specific rules regarding withdrawals and distributions.

Age and Tax Considerations

While funds can be withdrawn from a 401(k) plan at any time, distributions before the age of 59½ are generally subject to a 10% early withdrawal penalty in addition to regular income tax.

After reaching age 59½ , withdrawals are taxed as ordinary income. However, for Roth 401(k) distributions, withdrawals are tax-free if the account has been held for at least five years and the account holder is at least 59½ years old.

Types of Withdrawals

There are several types of withdrawals from a 401(k) plan, each with its own rules and tax implications.

These include hardship withdrawals, which may be allowed for immediate and heavy financial needs; required minimum distributions, which are mandatory withdrawals that start at age 73.

There are also normal distributions, which can be taken upon retirement or after age 59 ½.


Under certain circumstances, a 401(k) plan participant may be able to take out a loan from their plan. However, there are strict rules around this.

Criteria for Taking a Loan From a 401(k) Plan

Some 401(k) plans permit loans, allowing participants to borrow against their account balance. The maximum loan amount is generally the lesser of 50% of the vested account balance or $50,000.

However, taking a loan from a 401(k) plan should be a last resort due to the potential impact on retirement savings growth.

Repayment Terms and Consequences

401(k) loans must be repaid, typically within five years, through payroll deductions. If a borrower fails to repay the loan on time, the outstanding balance is treated as a taxable distribution.

Moreover, if a borrower leaves their job, the loan often becomes due more quickly, potentially leading to financial hardship.

Rollovers and Transfers

Rollovers and transfers are mechanisms that allow participants to move their 401(k) funds to another retirement account.

Moving Funds From One 401(k) Plan to Another

Participants can move their 401(k) funds from one employer's plan to another when they change jobs.

This is known as a rollover. Direct rollovers, where funds are transferred directly between plan administrators, are not subject to taxes or penalties.

Rollovers to Individual Retirement Accounts (IRAs)

Alternatively, participants can rollover their 401(k) funds to an Individual Retirement Account (IRA) when they leave a job.

Both Traditional and Roth IRAs offer broader investment options than most 401(k) plans, but they also have different rules regarding contributions, distributions, and taxes.

Plan Termination and Distribution Options

In the event that a 401(k) plan is terminated, there are specific rules governing the handling of funds and distribution options for participants.

Handling of Funds Upon Plan Termination

If a 401(k) plan is terminated, all participants become 100% vested in their account balances.

The plan administrator is typically responsible for distributing these funds either directly to the participants or by rolling them over into another qualified retirement plan.

Distribution Options for Participants

When receiving a distribution from a terminated 401(k) plan, participants can choose to take a lump-sum distribution, roll over the funds into another retirement account, or in some cases, annuitize the distribution to receive a steady stream of income.

Compliance and Regulations

401(k) plans are governed by several federal laws and regulations to ensure they operate in the best interests of participants.

ERISA (Employee Retirement Income Security Act)

ERISA is a federal law that sets standards for most voluntarily established retirement plans to provide protection for individuals in these plans.

It requires plans to provide participants with plan information, imposes fiduciary responsibilities on plan managers, and ensures plans can pay benefits.

IRS Regulations and Reporting Requirements

The Internal Revenue Service (IRS) sets contribution limits and tax rules for 401(k) plans and requires regular reporting from plan administrators.

These regulations and requirements are designed to ensure that the plans are being operated in accordance with tax laws and for the exclusive benefit of participants and their beneficiaries.

401(k) Plan Rules


Understanding the rules of 401(k) plans is crucial for effectively utilizing these retirement savings vehicles.

The eligibility criteria determine who can participate, while enrollment processes vary among employers.

Contributions are a key aspect, with employees being able to defer a portion of their salary and employers often offering matching contributions.

Vesting schedules determine the ownership of employer contributions. Investment options play a vital role in maximizing returns, requiring participants to choose wisely based on their risk tolerance and goals.

Withdrawal rules, including age and tax considerations, must be carefully followed to avoid penalties. Loans from 401(k) plans are possible but should be a last resort due to potential consequences.

Rollovers and transfers allow for flexibility in moving funds. Compliance with laws such as ERISA and IRS regulations ensures the proper operation and protection of participants.

Adhering to these rules allows individuals to optimize their 401(k) plans for long-term financial security.

Rules of 401(k) Plans FAQs

About the Author

True Tamplin, BSc, CEPF®

True Tamplin is a published author, public speaker, CEO of UpDigital, and founder of Finance Strategists.

True is a Certified Educator in Personal Finance (CEPF®), author of The Handy Financial Ratios Guide, a member of the Society for Advancing Business Editing and Writing, contributes to his financial education site, Finance Strategists, and has spoken to various financial communities such as the CFA Institute, as well as university students like his Alma mater, Biola University, where he received a bachelor of science in business and data analytics.

To learn more about True, visit his personal website or view his author profiles on Amazon, Nasdaq and Forbes.

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