SIMPLE IRA, SEP or 401(k): Retirement Plans for Small Businesses

A plain comparison of SEP, SIMPLE IRA and 401(k) plans using IRS and Department of Labor rules, 2026 limits and startup tax credits.

Web Health Benefits · Last reviewed October 26, 2026 · 6 min read

A workplace retirement plan can keep paying off for employees decades later. For a small business, the hard part is choosing the kind that fits your size, budget and appetite for paperwork.

This guide compares the three plan types small employers most often weigh, the SEP, the SIMPLE IRA and the 401(k). It is general information, not tax, legal or investment advice. Limits change every year, so confirm details with a tax professional or plan provider before you commit.

The SEP: employer money only, flexible year to year

A Simplified Employee Pension (SEP) lets the employer contribute to traditional IRAs set up for each eligible employee. According to the IRS, a business of any size, even a self-employed person, can establish one, and only the employer contributes.

Key features, based on the IRS SEP page (updated May 2026):

Contributions are flexible. You don't have to contribute every year, which can help if cash flow swings.
When you do contribute, the rate must be uniform. The IRS says the employer "must contribute equally for all eligible employees."
Employees are always 100% vested in SEP money, and participant loans aren't permitted.
The employer generally has no annual filing requirement.

For 2026, the Department of Labor and IRS publication Choosing a Retirement Solution for Your Small Business lists the SEP maximum as up to 25% of compensation but no more than $72,000. The same publication says, for 2026, a SEP must be offered to all employees who are at least 21, have worked for you in 3 of the last 5 years and earned at least $800.

The SIMPLE IRA: a required employer contribution, light administration

A Savings Incentive Match Plan for Employees (SIMPLE) IRA lets employees save through payroll and requires the employer to contribute. The IRS describes it as available to any small business, generally with 100 or fewer employees, and the employer "cannot have any other retirement plan."

The IRS SIMPLE IRA page (updated April 2026) says the employer must contribute each year using one of two formulas: a dollar-for-dollar match of up to 3% of compensation, or a 2% nonelective contribution for every eligible employee whether or not they save. The same page describes newer options created by the SECURE 2.0 Act for some employers, so read the current page if you are comparing formulas.

For 2026, IRS news release IR-2025-111 says employees can contribute up to $17,000 to a SIMPLE account, with a catch-up limit of $4,000 for those 50 and over in most SIMPLE plans.

Other rules worth knowing, all from the IRS SIMPLE IRA page as of 2026:

Timing. You can set up a SIMPLE IRA effective on any date from January 1 through October 1 of a year if you haven't had one before; if you previously maintained one, it can only start on January 1.
Election period. Each year employees get an election period of at least 60 days to set their contribution levels, with notice beforehand.
Vesting and withdrawals. Employees are always 100% vested. Withdrawals before 59 1/2 generally face a 10% additional tax, rising to 25% within the first two years of participation.

The 401(k): the most flexible, with the most responsibility

A 401(k) lets employees defer part of their pay into individual accounts, and employers may add matching or other contributions. For 2026, IR-2025-111 sets the employee deferral limit at $24,500, with an $8,000 catch-up for most participants 50 and older and a higher $11,250 catch-up for those aged 60 through 63.

The IRS 401(k) overview describes three main types:

Traditional 401(k). Employer contributions can vest over time, but the plan must pass annual nondiscrimination tests (the ADP and ACP tests) to show it doesn't favor highly compensated employees.
Safe harbor 401(k). Employer contributions must be fully vested when made, and the plan is not subject to those annual tests. Eligible employees must get a written notice of their rights and obligations.
SIMPLE 401(k). The IRS overview (updated August 2026) says it is available to employers with 100 or fewer employees who received at least $5,000 in compensation the previous year; employer contributions are fully vested and the annual tests don't apply.

The DOL and IRS small-business publication notes that 401(k) and profit-sharing plans have no model form to set up the plan and must file an annual Form 5500, unlike SEPs and SIMPLE IRAs.

Your duties as a plan sponsor

With a 401(k) in particular, the people who run the plan take on fiduciary responsibilities under federal law. The Department of Labor's booklet Meeting Your Fiduciary Responsibilities lists core duties: acting solely in the interest of participants, acting prudently, diversifying plan investments and paying only reasonable plan expenses. It recommends documenting decisions and the reasons for them.

It also says those who handle plan funds generally must be covered by a fidelity bond, and that employee contributions must be deposited as soon as they can reasonably be separated from company assets. For plans with fewer than 100 participants, it says deposits made no later than the 7th business day after withholding are considered compliant.

Tax credits that help with startup costs

The IRS offers credits to offset the cost of starting a plan. As of 2026, its retirement plans startup costs tax credit page says eligible employers with 100 or fewer employees (counting those paid at least $5,000) may claim a credit for three years of up to $5,000 a year (the exact cap depends on how many non-highly compensated employees are eligible) toward the ordinary and necessary costs of starting a SEP, SIMPLE IRA or qualified plan such as a 401(k). The page says the credit covers 100% of eligible costs for employers with 50 or fewer such employees and 50% for those with 51 to 100.

As of 2026, the same IRS page also describes an auto-enrollment credit of $500 a year for three years, and a separate credit for employer contributions, worth up to $1,000 per employee in early years for employers with 1 to 50 employees. You can't both deduct the startup costs and claim the credit for the same expenses. The credit is claimed on Form 8881.

A quick way to narrow the choice

Do you want employees to save from their own pay? If yes, a SEP alone won't do it, because only the employer contributes.
Can you commit to an employer contribution every year? A SIMPLE IRA requires one; a SEP lets you skip lean years.
Do you already sponsor another retirement plan? If so, the IRS says a SIMPLE IRA isn't available.
Do you want higher savings limits, vesting schedules or more design options? A 401(k) offers more, in exchange for more administration.

For example, a hypothetical six-person landscaping company with uneven profits might lean toward a SEP, while a steady 30-person firm whose staff want to save more might compare a safe harbor 401(k) with a SIMPLE IRA.

Checking who you work with

The SEC's Investor.gov advises checking whether an investment professional is registered with the SEC or a state securities regulator before hiring them, and reading the firm's relationship summary (Form CRS), which describes services, fees and conflicts of interest. Be wary of anyone who pressures you to decide quickly or can't clearly explain every fee.

For personal help, the IRS and the Department of Labor's Employee Benefits Security Administration offer free guidance, and a CPA or benefits attorney can review your plan design.

Key takeaways

A SEP is employer-funded, flexible year to year and simple to run; for 2026 the cap is 25% of pay up to $72,000, per the DOL and IRS publication.
A SIMPLE IRA requires an employer match or nonelective contribution and suits employers with 100 or fewer employees and no other plan.
A 401(k) has the highest 2026 employee limit ($24,500, per IRS release IR-2025-111) but more testing, filing and fiduciary work.
IRS startup and auto-enrollment credits can offset early costs for small employers.

Sources

Our articles are general information, not financial, insurance, tax or legal advice, and we don't sell insurance or recommend specific companies or products.

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