A type of deferred compensation plan, and now the most popular type of plan by far, the 401(k) plan allows contributions to be funded by the participants themselves, rather than by the employer. Employees elect to forgo a portion of their salary and have it put in the plan instead. These plans can be expensive to administer, but the employer’s contribution cost is generally very small (employers often offer to match employee deferrals as an incentive for employees to participate). Thus, in the long run, 401(k) plans tend to be relatively inexpensive for the employer.

The requirements for 401(k) plans are complicated, and several tests must be met for the plan to remain in force. For example, the higher-paid employees’ deferral percentage cannot be disproportionate to the rank-and-file’s percentage of compensation deferred.

However, you don’t have to perform discrimination testing if you adopt a “safe harbor” 401(k) plan. With a safe harbor 401(k) plan, you generally have to either match your employees’ contributions (100% of employee deferrals up to 3% of compensation, and 50% of deferrals between 3% and 5% of compensation), or make a fixed contribution of 3% of compensation for all eligible employees, regardless of whether they contribute to the plan. Your contributions must be fully vested immediately.

You can also avoid discrimination testing by adopting a qualified automatic contribution arrangement, or QACA. Under a QACA, an employee who fails to make an affirmative deferral election is automatically enrolled in the plan. An employee’s automatic contribution must be at least 3% for the first two calendar years of participation and then increase 1% each year until it reaches 6%. You can require an automatic contribution of as much as 15%. Employees can change their contribution rate, or stop contributing, at any time (and get a refund of their automatic contributions if they elect out within 90 days). As with safe harbor plans, you’re required to make an employer contribution: either 3% of pay to each eligible employee, or a matching contribution, but the match is a little different — dollar for dollar up to 1% of pay, and 50% on additional contributions up to 6% of pay. You can also require two years of service before your contributions vest (compared to immediate vesting in a safe harbor plan).

Another way to avoid discrimination testing is by adopting a SIMPLE 401(k) plan. These plans are similar to SIMPLE IRAs (see below), but can also allow loans and Roth contributions. Because they’re still qualified plans (and therefore more complicated than SIMPLE IRAs), and allow less deferrals than traditional 401(k)s, SIMPLE 401(k)s haven’t become a popular option.

If you don’t have any employees (or your spouse is your only employee) an “individual” or “solo” 401(k) plan may be especially attractive. Because you have no employees, you won’t need to perform discrimination testing, and your plan will be exempt from the requirements of the Employee Retirement Income Security Act of 1974 (ERISA). You can make pre-tax contributions of up to $20,500 in 2022 (up from $19,500 in 2021), plus an additional $6,500 of pre-tax catch-up contributions if you’re age 50 or older. You can also make profit-sharing contributions; however, total annual additions to your account in 2022 can’t exceed $61,000 (plus any age-50 catch-up contributions).

Note: A 401(k) plan can let employees designate all or part of their elective deferrals as Roth 401(k) contributions. Roth 401(k) contributions are made on an after-tax basis, just like Roth IRA contributions. Unlike pre-tax contributions to a 401(k) plan, there’s no up-front tax benefit — contributions are deducted from pay and transferred to the plan after taxes are calculated. Because taxes have already been paid on these amounts, a distribution of Roth 401(k) contributions is always free from federal income tax. And all earnings on Roth 401(k) contributions are free from federal income tax if received in a “qualified distribution.”

Note: 401(k) plans are generally established as part of a profit-sharing plan.