Retirement Accounts That Slash Your Self-Employment Taxes: Solo 401(k) vs SEP IRA (2026)
By TraxGig Team · June 30, 2026 · 11 min read
Most tax deductions cost you money — you spend on software or equipment, and the write-off softens the blow. Retirement contributions are the rare exception: the money stays yours, growing for your future, while still lowering your tax bill today. For self-employed people, who have no employer 401(k) match to fall back on, these accounts are one of the most powerful tools available. This guide compares the three main options and helps you pick the one that lets you save — and deduct — the most.
Why this matters more when you're self-employed
A traditional employee gets a 401(k) handed to them, often with a match. You have to set your own up — but in exchange, you get access to accounts with far higher contribution limitsthan a typical employee's 401(k), and every dollar you contribute to a traditional version reduces your taxable income. Skip them and you leave one of the biggest legal tax reductions on the table year after year.
The core mechanic: a traditional (pre-tax) contribution comes off your taxable income now. Put $20,000 into a Solo 401(k) and you may cut your taxable income by $20,000 — potentially saving thousands in tax while that full $20,000 keeps working for your retirement.
Option 1: SEP IRA — the simple powerhouse
The SEP IRA (Simplified Employee Pension) is the easiest self-employed retirement account to open and run. It has almost no paperwork and no annual filing requirements.
- Contribution limit: up to 25% of your net self-employment earnings, capped at a high annual limit that adjusts each year (in the neighborhood of $70,000).
- Best for: people who want maximum simplicity, and higher earners who can hit the 25% comfortably.
- Trade-off:because contributions are a straight percentage of income, lower earners can't contribute as much as they could with a Solo 401(k).
Option 2: Solo 401(k) — the maximizer
The Solo 401(k)(also called an Individual 401(k)) is for self-employed people with no employees other than a spouse. It has a little more setup, but it's the most flexible and often lets you contribute more — especially at low-to-moderate incomes — because you contribute in two capacities:
- As the employee:you can defer up to the annual employee limit (a set dollar amount, plus a catch-up if you're 50+).
- As the employer: you can add up to 25% of your net earnings on top.
That two-part structure is the key advantage. Because the employee portion is a flat dollar amount rather than a percentage, someone with a modest income can often contribute far more to a Solo 401(k) than to a SEP IRA at the same income.
Example: on $50,000 of net earnings, a SEP IRA might cap you around $10,000 (25%). A Solo 401(k) lets you first defer a large flat employee amount and then add the 25% employer portion — potentially doubling what you can contribute and deduct on the same income.
Solo 401(k)s also offer two features a SEP IRA doesn't:
- A Roth option — contribute after-tax dollars for tax-free growth and withdrawals, useful if you expect higher taxes later.
- Loan access— many plans let you borrow from your balance, a flexibility IRAs don't allow.
Option 3: SIMPLE IRA — the middle ground
The SIMPLE IRAsits between a personal IRA and the bigger plans. Its contribution limits are lower than a SEP or Solo 401(k), so for a solo business owner it's usually not the top choice — but it can make sense for a small business with a few employees that wants an easy plan to offer everyone.
Side-by-side comparison
| Feature | SEP IRA | Solo 401(k) |
|---|---|---|
| Setup complexity | Very easy | Moderate |
| Contribution structure | 25% of net earnings | Employee deferral + 25% employer |
| Best at lower income | Less | More (flat employee portion) |
| Roth option | No | Often yes |
| Loans allowed | No | Often yes |
| Annual filing | None | Required once balance is large |
| Can have employees | Yes | No (spouse only) |
Which should you choose?
- Want the absolute simplest option? A SEP IRA opens in minutes and has no ongoing admin.
- Want to contribute the most, especially at moderate income? A Solo 401(k) usually wins thanks to the two-part contribution.
- Want a Roth option or the ability to borrow?Solo 401(k), which SEP IRAs can't match.
- Have employees beyond a spouse? A SEP or SIMPLE IRA, since a Solo 401(k) is only for owner-and-spouse businesses.
The timing detail that catches people
Deadlines differ by account and contribution type. A SEP IRA can often be opened and funded right up until your tax filing deadline, letting you make a prior-year contribution after the year ends. A Solo 401(k)'s employeedeferral generally needs to be elected by year-end, even if the money goes in later. If you're counting on a big contribution to reduce last year's taxes, confirm the deadline for your specific account so you don't miss the window.
How it fits your overall tax strategy
Retirement contributions reduce your income tax, though not the self-employment tax portion. Combined with tracking every business deduction, they form the two-part foundation of paying less: deductions shrink your taxable profit, and retirement contributions shrink what's left — all while the retirement money stays yours.
Knowing how much you can afford to contribute starts with knowing your real net profit. TraxGig keeps your income and deductions current, so you can size a year-end retirement contribution with confidence. Start tracking free.
The bottom line
A SEP IRA and a Solo 401(k) both let you turn a chunk of this year's income into tax savings and future wealth at the same time. The SEP wins on simplicity; the Solo 401(k) usually wins on how much you can contribute — especially at low-to-moderate incomes — and adds Roth and loan flexibility. For most solo earners looking to maximize, the Solo 401(k) is the stronger choice. Either way, funding one is among the smartest moves a self-employed person can make.
Related reading
This article is for general educational purposes and is not tax or investment advice. Contribution limits, deadlines, and rules change and depend on your situation — consult a qualified tax professional or financial advisor.