S-Corp SIMPLE IRA Contributions: The October 1 Setup Deadline
A SIMPLE IRA sounds like the easy retirement plan for a small S-corp — no Form 5500, no discrimination testing, and for 2026 a deferral limit that can run as high as $18,100. For a one- or two-person S-corp it usually is easier than a 401(k). But it comes with two rules that trip up owners who assume they can set one up the way they’d set up a SEP: the plan has to be in place by October 1, and it can’t run alongside any other retirement plan your corporation sponsors. Miss either one, and the contribution you were counting on for this year doesn’t happen.
The October 1 Deadline You Can’t Work Around
A SIMPLE IRA has to exist before most of the year it covers has already happened. The IRS lets you set one up effective any date from January 1 through October 1 of a given year, provided your corporation didn’t already maintain one before that. Once October 1 passes, that window is closed for the year — there’s no equivalent to the SEP’s grace period, which lets you adopt and fund a plan as late as your extended Form 1120-S due date. If you’re weighing this option for the current year after October 1 has already passed, the answer is that you can’t start one. The earliest effective date is January 1 of the following year, with deferrals beginning once payroll runs under the new plan.
You Can’t Run It Next to a 401(k) or SEP
It’s an either/or plan, not an add-on. An employer that maintains this kind of plan for a calendar year can’t also maintain any other qualified retirement plan for that same year — not a 401(k), not a SEP, not a profit-sharing plan. An S-corp that already runs a 401(k) under SECURE 2.0 or funds a SEP-IRA can’t layer this on top to shelter more income in the same year. The choice has to be made at the plan level, for the whole corporation, before the year starts. The lone exception runs in the other direction: since 2024, SECURE 2.0 lets an employer terminate a SIMPLE IRA mid-year and replace it with a safe harbor 401(k), with that year’s deferral limit prorated between the two plans — there’s a mid-year path out of a SIMPLE, but never into one.
Your Compensation Is W-2 Wages, Not Distributions
What counts as your compensation follows the same rule as every other retirement plan on this site. Your SIMPLE IRA deferrals and any employer contribution are based on the wages your S-corp actually paid you and reported in Box 1 of your W-2, plus the deferral itself — not your K-1 pass-through income and not the distributions you took on top of salary. An owner who pays a modest salary and takes the rest as a distribution can only defer against that salary, no matter how much the corporation earned. Section 1372 of the Internal Revenue Code treats a 2-percent-or-greater shareholder as a partner for specific fringe-benefit provisions — group-term life insurance, health coverage, cafeteria plans — but qualified retirement plans aren’t on that list. For this purpose, a 2% shareholder-employee is treated exactly like any other W-2 employee, the same as the SEP-IRA rules already in place here.
The 2026 SIMPLE IRA Limits — and Why Yours Is Probably Higher
The number most advisors quote for a SIMPLE IRA isn’t the number most S-corp owners actually get. The standard 2026 salary reduction limit is $17,000, with a $4,000 catch-up for employees 50 and over. SECURE 2.0 automatically raises the deferral limit for any employer with 25 or fewer employees — no election required and no richer match needed to earn it. For 2026 that enhanced limit is $18,100, paired with its own catch-up of $3,850 for employees 50 and older — $150 lower than the standard catch-up, a quirk of how the two amounts are indexed, though the combined ceiling of $21,950 still beats the standard plan’s $21,000. Employees who turn 60, 61, 62, or 63 during the year get a larger catch-up of $5,250 instead, under either tier. A one- or two-person S-corp almost always falls under the 25-employee threshold, which means $18,100 — not $17,000 — is usually the real ceiling.
Choosing Between the 3% Match and the 2% Nonelective
The corporation picks the employer contribution formula, and it applies to every eligible employee the same way. You can match salary deferrals dollar-for-dollar up to 3% of compensation — reducible to as low as 1% in no more than 2 of any 5 years — or make a flat 2% nonelective contribution to every eligible employee’s account regardless of whether they deferred anything, capped at $360,000 of compensation for 2026. For a solo owner who plans to defer the maximum anyway, the 3% match usually produces more total contribution dollars at the same salary. For an S-corp expecting to add eligible employees soon, the 2% nonelective can be the more predictable cost to plan around, since it doesn’t depend on what anyone else chooses to defer. Whichever formula you pick, employees have to be notified before the plan’s annual election period, which runs from November 2 through December 31.
What This Means Before You Fund the Next Contribution
None of this makes it the wrong plan for a small S-corp — it’s still the cheapest plan to administer, with no annual filing and no testing beyond the rules above. The real risk is timing: a decision between this plan, a SEP, and a 401(k) needs to be locked in well before October 1, not discovered after the window has already closed. We cover how the related plans stack up in our Retirement Plan Options for S-Corps resource and how the salary question underneath all of them gets set in S-Corp Reasonable Salary: How to Set One (and Why the IRS Is Watching). If you’re deciding which plan fits before next year’s window opens, talk to us before you commit to one, not after you’ve already missed the deadline.