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$ S-Corp Saver

What can your salary put into a Solo 401(k)?

Separate employee deferrals from employer contributions, account for another job’s 401(k), and compare a SEP-IRA using the same W-2 wages. Distributions do not create retirement contribution room.

Educational capacity estimate—not tax, legal, investment or plan-administration advice. Uses published 2026 limits. Sources checked . No account required.

Your 2026 contribution plan

One participant, one calendar-year S-corp, 2026 IRS limits. Amounts stay in this page’s memory—not in links, saved storage, or analytics. A spouse should run a separate calculation.

Ages 1–120. Catch-up starts at 50; ages 60–63 get a higher limit.

Before elective deferrals. Not net profit, distributions, or automatically W-2 Box 1. Confirm owner health-insurance and fringe adjustments with payroll.

Optional

Decides whether 2026 catch-up must be Roth. Not household income or this year’s salary. Leave blank if unknown.

Does your plan allow age-based catch-up contributions?

Applies at 50 or older. Yes adds catch-up room; No leaves it out; Not sure sends ages 50+ to plan review.

Does your plan offer Roth catch-up?

Needed only when catch-up applies and your 2025 FICA wages from this S-corp exceeded $150,000; then catch-up must be Roth.

Other employers and deposits already made

Combine all unrelated ordinary 401(k) plans. 403(b), SIMPLE, SARSEP, related-employer or mixed cases need administrator review.

Optional

Pretax and Roth employee deferrals combined. Exclude catch-up and employer contributions.

Optional

Separate from the basic amount above; confirm the split with that plan’s administrator.

Optional

Regular and catch-up employee deposits for 2026 already made.

Optional

2026 employer contributions already made to this plan only.

Confirm the planning assumptions

Amounts appear only when all five are Yes. Otherwise you get a list of what to check with your plan administrator. This is not an eligibility determination.

Are you an owner-employee of an S-corp that uses a calendar tax year?

Unlocks the 2026 limits applied to your W-2 wages. Sole proprietors and fiscal-year plans use different math.

Does the plan cover only you, and optionally your spouse, with no eligible nonspouse employees?

Unlocks one-participant plan rules. Eligible employees bring coverage and testing rules this tool doesn’t model.

Is this S-corp free of related employers, a controlled group, and any other retirement plan?

Unlocks treating this plan’s limits as unshared. Related employers and other plans can share them.

Are the wages you entered plan-eligible cash wages subject to employee FICA, and does the plan allow both employee deferrals and employer profit-sharing?

Unlocks the 25%-of-wages employer limit and the payroll-funding check, which both use those wages.

Will remaining 2026 payroll and business cash fund the contributions you choose, with employee elections made by the plan’s deadline?

Unlocks the remaining-to-contribute amounts. This asks whether payroll can carry deferrals you pick, not whether you can fund the maximum.

Still unconfirmed: Calendar-year S-corp owner-employee; Owner-only plan; No related employers or other plans; Plan-eligible wages and formula; Payroll, cash and election timing.

Salary first. Retirement capacity second.

For an S-corp owner-employee, employer profit-sharing and SEP contributions use plan-eligible W-2 compensation—not Schedule C net earnings, S-corp profit or distributions. Confirm the plan’s compensation definition with payroll, including elective-deferral add-backs and any owner health-insurance or fringe-benefit adjustments. Do not blindly copy W-2 Box 1.

Start with a documented reasonable salary. A higher salary can create more employer contribution room, but also changes payroll taxes and other deductions. This is not a recommendation to raise salary just to fund a plan. The home S-corp savings calculator does not include retirement contributions in its tax comparison.

Published 2026 limits

Every dollar limit below comes from IRS Notice 2025-67. Age means age at the end of 2026.

Basic employee deferrals, across employers (§402(g))
$24,500
Catch-up, ages 50–59 or 64+, if permitted
$8,000
Higher catch-up, ages 60–63, if permitted
$11,250
Annual additions, excluding catch-up (§415(c))
$72,000
Compensation considered (§401(a)(17))
$360,000

Annual additions are also limited to 100% of compensation. The modeled employer profit-sharing ceiling is 25% of eligible wages; SEP capacity is the lesser of 25% of those wages or $72,000. Catch-up is employee money and sits outside the annual-additions cap, not outside the employee’s own compensation limit.

How the calculation works

  1. Cap plan-eligible wages at $360,000. The annual-additions ceiling is the lesser of those wages or $72,000.
  2. Subtract basic deferrals at unrelated employers from $24,500, and separately subtract catch-up used elsewhere from your applicable age-based catch-up limit. Both Roth and pretax deferrals count. A governmental 457(b) has a separate limit; its entered deferrals do not reduce this 401(k) room.
  3. First find the legal employee-first allocation. Then reserve employee Social Security and Medicare withholding from wages. If that payroll-funded ceiling is lower than the legal employee target, fill employer room first (while preserving recorded employee deposits) and fit employee deferrals into the remaining room. This preserves the total wherever payroll can fund it.
  4. Classify catch-up as the greater of zero, employee contributions above remaining basic deferral room, or employee plus employer contributions above the annual-additions ceiling. Catch-up can therefore be required even when employee contributions are below $24,500.
  5. Subtract employee and employer deposits already made once, from their respective annual targets. Reject excess deposits or unsupported configurations instead of displaying negative remaining room.
For your plan administrator: allocation formulas

Let W = capped wages, B = min($72,000, W), D = remaining basic room, C = remaining catch-up room, X = employee deposits already made, Y = employer deposits already made, and Pcap = min(25% × W, B), rounded down to cents.

Legal employee target L = min(W, D + C, max(0, B − Y + C)). Payroll-funded ceiling F = W less employee FICA withholding. If L ≤ F: employee E = L, employer P = min(Pcap, max(0, B − max(0, E − C))). If L > F: P = min(Pcap, max(0, B − max(0, X − C))); E = min(F, D + C, max(0, B − P + C)).

The annual employee FICA reserve combines Social Security and Medicare and rounds up to a whole cent; the payroll-funded ceiling cannot be negative. This conservative annual reserve is not a pay-period payroll calculation.

Catch-up K = max(0, E − D, E + P − B); regular employee = E − K. We require X ≤ E, Y ≤ P, K ≤ C, regular employee ≤ D, and regular employee + P ≤ B. This is one compatible allocation; maximum employee and employer figures cannot be independently stacked.

For example, at $120,000 of wages, age 45, no outside deferrals and no deposits, the 2026 estimate is $24,500 employee + $30,000 employer = $54,500, versus a $30,000 SEP. At $25,000 of wages and age 45, employer-first allocation gives $18,750 employee + $6,250 employer = $25,000, leaving enough wages for $1,912.50 of employee FICA. At $20,000 of wages and age 50 with catch-up permitted, reserve $1,530 for employee FICA: $18,470 employee + $5,000 employer = $23,470, with $3,470 of employee contributions classified as catch-up. The legal $25,000 total is not payroll-funded in that last case. These are derived illustrations, not IRS-published examples, and exclude income-tax withholding and other payroll deductions.

The payroll ceiling assumes the entered compensation is cash W-2 wages subject to employee FICA. Under IRS Topic 751, employee Social Security is 6.2% up to the 2026 $184,500 wage base and employee Medicare is 1.45% without that cap: a combined 7.65% at the low wages where this restriction binds. Deferrals do not eliminate these payroll taxes. Payroll rounding, income-tax withholding (including on Roth catch-up), noncash benefits and other deductions may further reduce what you can contribute; confirm the actual payroll calculation.

The personal deferral ceiling is shared across employers. In contrast, the annual-additions limit applies separately to unrelated employers; another employer’s match does not use this S-corp’s room. Related businesses, controlled groups and special 403(b) aggregation rules require review. The SEP comparison is an alternative plan, not extra room on top of your Solo 401(k).

The 2026 high-earner Roth catch-up rule

Beginning in 2026, if your prior-year FICA wages from the employer sponsoring this plan exceeded $150,000, catch-up contributions must be designated Roth. Exactly $150,000 does not trigger the rule; more than $150,000 does. This is not household income, AGI or your current-year salary. See the IRS catch-up guidance and Notice 2025-67.

Required Roth catch-up is not a pretax deduction. If catch-up is needed but prior-year wages or necessary plan permissions are unknown, the planner asks for administrator review rather than presenting an unsupported maximum. Plans can impose stricter limits. Confirm that a plan permits the higher age-60–63 amount, where applicable.

Year-end: an election is not a deposit

Publication 560’s elective-deferral definition says owner/employees must elect employee deferrals by the end of the tax year and may then fund them by the tax-return filing deadline, including extensions. For an S-corp’s contribution deduction, use the corporation’s Form 1120-S return deadline—not the shareholder’s personal Form 1040 deadline—and confirm whether plan or deposit rules require earlier funding. For a calendar-year owner, a 2026 election is due by December 31, 2026—not retroactively next filing season.

For S-corp W-2 payroll, there is another essential restriction: Treasury regulation §1.401(k)-1(a)(3)(iii) requires the election before compensation is currently available, and after the cash-or-deferred arrangement is adopted/effective. Arrange the plan and election before the relevant payroll is paid or available. December 31 is not permission to reclassify wages already received, and a December 31 bank transfer alone does not fix a missing election.

Employer contributions generally can be funded by the employer’s return due date, including extensions, under Publication 560. SEP establishment and contribution deadlines can also extend to that return deadline. Plan adoption, employee elections, payroll reporting and deposit deadlines are distinct; confirm your entity and plan’s deadlines with the administrator. The special first-year post-year-end employee-deferral rule for sole proprietors is not an S-corp rule.

What this planner does not cover

  • Eligible nonspouse employees, controlled groups, related employers, multiple plans at the same sponsor, or non-calendar-year plans. These need administrator review.
  • Schedule C/partnership earned-income calculations, SIMPLE or special 403(b)/SARSEP rules, or the cross-plan catch-up exception when an individual plan does not allow catch-up.
  • Non-Roth after-tax “mega-backdoor” contributions, forfeitures, defined-benefit plans, or plan-specific allocation and nondiscrimination testing.
  • Income-tax withholding, other payroll deductions, noncash compensation adjustments, a remaining-payroll schedule, or actual cash availability. The employee FICA reserve is modeled, but the estimate still relies on your payroll, timing and plan confirmations.
  • Income-tax savings, QBI effects, state taxes, investment returns or whether pretax versus Roth is better. A maximum contribution is not necessarily a maximum deduction.

Form 5500-EZ filing obligations can apply when combined year-end assets across the employer’s one-participant plans exceed $250,000, and in the final plan year regardless of that threshold. See the IRS Form 5500-EZ instructions (currently the 2025 edition); confirm the applicable filing-year instructions with your administrator. This calculator does not determine filing obligations.

Sources

Checked against source guidance October 23, 2026. Historical IRS examples are used to check the calculations with their original limits; estimates on this page use 2026 limits only.