SEP IRA vs Solo 401(k): Best Retirement Plan for Self-Employed 2026

Compare contribution limits, tax benefits, and flexibility between SEP IRAs and Solo 401(k)s to maximize retirement savings as a self-employed worker.

By Muhammad AkbarLast reviewed October 24, 2026How we calculate

Contribution Limits

SEP IRA: up to 25% of net earnings, max $69,000 (2026). Solo 401(k): employee deferral up to $23,500 plus employer contribution up to 25% of compensation, total max $69,500 — plus $7,500 catch-up if 50+. Solo 401(k) allows bigger contributions at lower income levels.

The $80K Income Example

At $80,000 net profit: SEP IRA allows roughly $14,800 (25% of adjusted earnings). Solo 401(k) allows $23,500 deferral plus ~$14,800 employer = $38,300. The Solo 401(k) roughly doubles your tax-deferred savings at this income level.

Administrative Burden

SEP IRA: open with a brokerage in minutes, no IRS filing until assets exceed $250,000 (Form 5500-EZ). Solo 401(k): slightly more setup (plan document), but major brokers offer template plans with no annual fees. Both are dramatically simpler than employer 401(k)s.

Which Should You Choose?

Choose Solo 401(k) if you want maximum contributions, Roth options, or catch-up contributions. Choose SEP IRA if you want zero paperwork, have employees (SEP covers them too — Solo 401(k) cannot), or started mid-year and want a dead-simple plan.

Frequently Asked Questions

Can I have both a SEP IRA and Solo 401(k)?

You can maintain both, but contribution limits interact — the employer-side 25% limit applies across both plans combined. Maintaining two plans adds paperwork without extra contribution room for a solo owner.

Which plan is better at $50,000 income?

At $50,000 net profit, SEP allows ~$9,300. Solo 401(k) allows $23,500 deferral (or 100% of compensation, whichever is less) — effectively your entire adjusted income. Solo 401(k) wins at almost every income level for solo owners.

When is the contribution deadline?

Both plans allow contributions until your tax filing deadline including extensions (October 15). However, Solo 401(k) employee deferrals must be elected by December 31. Open a Solo 401(k) by December 31 to make deferrals for that year.

Sources

IRS Revenue Procedure 2025-32 — 2026 inflation adjustments — tax brackets, standard deduction, QBI thresholds.
IRS Schedule SE instructions — Self-employment tax: the 92.35% adjustment, the Social Security wage base, the Medicare surtax.
IRS Form 1040-ES — Estimated tax deadlines and the safe-harbour rules used for the quarterly schedule.
IRS Publication 334 — Tax guide for small business — deductible expenses and net profit.
IRS Social Security wage base — The $184,500 Social Security cap applied for 2026.

How these numbers are produced

Calculations follow the order of operations on the IRS forms themselves: net profit, the 92.35% adjustment, self-employment tax, the 50% deduction against AGI, the standard deduction, the §199A QBI deduction with its phase-out, then the federal brackets. State tax is computed separately on state AGI less that state's own standard deduction, because no state allows the federal QBI deduction and almost none allow the federal standard deduction.

What it does not cover. The calculators model a single filer or a married couple filing jointly with self-employment income as the main source. They do not model local income taxes, W-2 wages held alongside freelance work, itemized deductions, the alternative minimum tax, or credits. Where a local income tax exists, it is described on that state's page.

Not advice. SelfTaxCalc produces estimates, not tax advice. No one here is a CPA, an enrolled agent or a tax attorney, and nothing on this site creates a professional relationship. Estimates are a starting point for planning and for a conversation with a professional — they are not a substitute for one.