Best Retirement Plans for Small Business Owners: 401(k), SEP, SIMPLE and Cash Balance Compared

Retirement plans for business owners are chosen on three questions: how much profit is there to shelter, who else works here, and how much administration the owner will tolerate. The 401(k) plans for business owners, the SEP and SIMPLE IRAs and the defined benefit designs answer them differently. The figures below are the 2026 limits from Notice 2025-67; the rules are from Publication 560 and the IRS plan pages cited at the end.

The 2026 numbers every plan uses

• Elective deferrals to a 401(k): $24,500. Catch-up at age 50: $8,000. Catch-up for those who reach 60, 61, 62 or 63 in 2026: $11,250.
• Annual additions to a defined contribution account (deferrals plus employer money, before catch-ups): $72,000 (IRC 415(c)).
• SIMPLE IRA deferrals: $17,000, or $18,100 for certain plans; catch-up $4,000, or $5,250 at ages 60 to 63.
• Compensation counted for any plan: $360,000. Highly compensated employee threshold: $160,000.
• Defined benefit plan annual benefit: $290,000 (IRC 415(b)).
• Catch-up contributions for 2026 to a 401(k) or similar plan (Notice 2025-67 excepts plans described in section 408(k) or (p), meaning SEPs and SIMPLEs) by anyone whose 2025 wages from the employer exceeded $150,000 must be designated Roth contributions.

Small business retirement plans compared

SEP IRA: the simplest, and employer money only

A SEP takes employer contributions of up to 25% of each participant's compensation, capped at $72,000 for 2026, with compensation counted up to $360,000; a self-employed owner uses 20% of net earnings after the contribution and half of self-employment tax (Publication 560). Employees cannot defer their own pay into it. Every employee who is 21, has worked for you in 3 of the last 5 years and earned at least $800 in 2026 must be covered, and the IRS model form requires the same percentage of pay for everyone (IRS SEP FAQ). Its advantages are the deadline (set up and funded as late as the return due date including extensions) and the paperwork: Form 5305-SEP is kept, not filed, and Publication 560 says using it will usually relieve the employer from filing annual plan returns. It fits badly when the owner wants deferrals on top of the 25%, or has several employees who would each cost the owner's percentage.

SIMPLE IRA: payroll deferrals with a fixed employer cost

A SIMPLE IRA is open to employers with 100 or fewer employees who earned $5,000 or more in the prior year, and it must be the only plan the employer contributes to (Publication 560). Employees defer up to $17,000 in 2026 ($18,100 in plans that adopt the higher limit), plus the $4,000 catch-up. The employer either matches dollar for dollar up to 3% of pay (a match as low as 1% is allowed in 2 of any 5 years) or contributes 2% of pay for every eligible employee. Deferrals must reach the account within 30 days after the end of the month they were withheld. The plan can be effective on any date from January 1 through October 1, unless the business came into existence after October 1, and it has no annual filing requirement (IRS SIMPLE IRA page). The cost of simplicity is the ceiling: an owner maxes out well below a 401(k), and withdrawals in the first two years of participation carry a 25% additional tax instead of 10%.

One-participant 401(k): the owner wears two hats

The IRS calls it a one-participant plan; providers call it a solo 401(k). It is an ordinary 401(k) that covers an owner with no employees, or the owner and a spouse (IRS one-participant 401(k) page). The owner defers up to $24,500 as an employee (plus catch-up) and the business adds up to 25% of compensation as employer, within the $72,000 annual additions limit before catch-ups. No nondiscrimination testing is needed until an employee becomes eligible, at which point the plan must cover that employee and pass the tests like any other 401(k). Form 5500-EZ is required once plan assets reach $250,000 at year end. Publication 560 adds a timing break for 2023 and later years: a sole proprietor with no employees can adopt the plan after year end, by the filing deadline without extensions, and first-year deferrals paid in by that date count for the first plan year.

401(k) with profit sharing, and the safe harbor version

With employees, a 401(k) becomes a plan for everyone who meets its eligibility rules. Employees defer through payroll; the employer can match and can add discretionary profit sharing, deductible up to 25% of the compensation of everyone in the plan (IRC 404(a)(3)), with each person's total capped at $72,000. Deferrals by highly compensated employees are tested against the rest of the staff each year (the ADP and ACP tests), and a top-heavy plan may owe minimum contributions for certain employees (IRS 401(k) overview).

A safe harbor 401(k) skips the ADP and ACP tests in exchange for a required, immediately vested employer contribution: a match of 100% of deferrals up to 3% of pay plus 50% of the next 2%, or a 3% nonelective contribution for every eligible non-highly compensated employee, with written notice to employees before the plan year for the matching design (IRC 401(k)(12); IRS 401(k) overview). A safe harbor plan that makes no other contributions is also exempt from the top-heavy rules (Publication 560). For an owner who wants to defer the full $24,500 without a test failure sending money back, the 3% is usually the price of admission. Deferrals only work when they run through payroll every pay period; BEG's Managed Payroll, from $25 per employee per month, handles the withholding, the deposits and the year-end W-2 codes.

Defined benefit and cash balance plans: for owners who want more than $72,000

A defined benefit plan promises a benefit, and the contribution is whatever an enrolled actuary certifies is needed to fund it, up to a benefit of $290,000 a year for 2026 (IRS benefit limits page). Because the contribution is driven by the benefit and the owner's age rather than by the $72,000 cap, it can be well above a 401(k) contribution for an owner closer to retirement age. The IRS lists the trade-offs plainly: employers can contribute and deduct more than under other plans, and it is the most costly and most administratively complex type, with a Form 5500 and a Schedule SB signed by the actuary every year and an excise tax if the minimum contribution is missed (IRS defined benefit plan page). The cash balance design, the combined deduction limit with a 401(k), and who it fits are in cash balance plan.

Same owner, three plans

The 401(k) wins by $32,500 over the SEP at the same salary because the deferral and catch-up sit on top of the same 25% employer contribution. The SEP would need $250,000 of wages to reach $62,500, and wages carry payroll tax. That interaction is the reason S corporation owners size the salary and the plan together.

S corporation owners: W-2 wages drive every contribution

The IRS is direct: distributions to an S corporation shareholder “do not constitute earned income for retirement plan purposes,” so deferrals and employer contributions are based on Form W-2 compensation (IRS S corporation retirement FAQ). An owner who keeps salary low to save payroll tax also caps the plan. What counts as a defensible salary is in S corp reasonable salary; the mechanics of paying it are in how to pay yourself from an S corp.

Startup credits for a first plan with employees

An employer with 100 or fewer employees who earned at least $5,000, at least one participant who is not highly compensated, and no plan for substantially the same employees in the prior three years can claim the section 45E credit on Form 8881: 100% of the ordinary and necessary costs of starting and administering a SEP, SIMPLE IRA or qualified plan with 50 or fewer employees (50% with 51 to 100), up to the greater of $500 or $250 per eligible non-highly compensated employee, capped at $5,000, for three years (IRS startup credit page; 26 U.S.C. 45E). Employer contributions to a defined contribution plan, SEP or SIMPLE earn a further credit of up to $1,000 per employee, 100% in the first two plan years and then 75%, 50% and 25%, reduced for employers over 50 employees, and adding automatic enrollment earns $500 a year for three years. Costs claimed as a credit cannot also be deducted. The full credit map for new companies is in tax credits for startups.

Which plan, at what salary, and whether a defined benefit layer belongs on top is a numbers question that Forward Tax Planning answers in writing before the adoption deadline, with your CPA and plan provider.

Sources: IRS, Notice 2025-67, 2026 cost-of-living adjusted limits for retirement plans; IRS, Publication 560 (2025), Retirement Plans for Small Business (SEP, SIMPLE, and Qualified Plans); IRS, Retirement plans FAQs regarding SEPs (reviewed August 1, 2026); IRS, SIMPLE IRA plan (plan sponsor page); IRS, One-participant 401(k) plans (reviewed April 9, 2026); IRS, 401(k) plan overview (plan sponsor page); IRS, Defined benefit plan (reviewed June 6, 2026); IRS, Retirement topics: defined benefit plan benefit limits (reviewed March 6, 2026); IRS, Retirement plan FAQs regarding contributions, S corporation (reviewed April 8, 2026); IRS, Retirement plans startup costs tax credit (reviewed May 31, 2026); IRS, Form 8881 (Rev. December 2025), Credit for Small Employer Pension Plan Startup Costs; 26 U.S.C. 404, deduction for contributions of an employer to an employees’ trust or annuity plan (404(a)(3), (a)(7)); 26 U.S.C. 45E, small employer pension plan startup costs; 26 U.S.C. 401, qualified pension, profit-sharing, and stock bonus plans (401(b)(2), 401(k)(12)). Figures and rules checked against these sources on September 26, 2026. This is general information, not tax advice for your situation. Tax services are provided by licensed tax professionals under a separate engagement agreement. BEG does not provide tax advice.