Roth vs Traditional IRA for the self-employed: SEP, Solo 401(k), SIMPLE
The self-employed retirement landscape changed significantly with SECURE 2.0 §601 (effective 2023), which permits Roth contributions inside SEP-IRA and SIMPLE IRA plans. Combined with the long-standing Roth Solo 401(k) and the optional Mega Backdoor inside a Solo 401(k), a self-employed worker now has more Roth-saving capacity than a comparable W-2 employee. The choice between vehicles depends on income, employee count, and operational complexity tolerance.
The four self-employed retirement vehicles
Solo 401(k) (also called Individual 401(k) or i401k). For a business with only the owner and spouse, no other employees. Two contribution buckets: employee elective deferral up to $23,500 (2026), plus employer contribution up to 25% of W-2 compensation or 20% of net self-employment earnings. Combined cap: $70,000 for 2026 ($77,500 with age-50 catch-up, $81,250 with ages 60-63 super catch-up). Roth available on the elective deferral. SECURE 2.0 §604 permits Roth employer contributions starting 2023, though plan documents had to be amended and many were not updated until 2024 or 2025.
SEP-IRA (Simplified Employee Pension). Operationally simpler than a Solo 401(k). Employer-only contributions up to 25% of compensation (or about 20% of net SE income after the half-SE-tax adjustment). 2026 cap: $70,000. Roth permitted since 2023 under SECURE 2.0 §601. No Form 5500 filing required until plan balance exceeds $250,000.
SIMPLE IRA. For small businesses with 100 or fewer employees who earned $5K+ in the prior year. Lower contribution limit ($16,500 in 2026 employee elective + 3% employer match or 2% non-elective). Roth permitted since 2023 under SECURE 2.0 §601. Operationally simpler than Solo 401(k) for businesses with employees.
Roth IRA (and Traditional IRA). The standard personal IRA at the standard $7,000 limit ($8,000 with catch-up). Available regardless of self-employment status, subject to the same income phase-outs as any W-2 worker. The self-employed person uses these in addition to (not instead of) the SEP, Solo 401(k), or SIMPLE.
SECURE 2.0 §601: the Roth SEP and Roth SIMPLE
Before 2023, SEP-IRA and SIMPLE IRA contributions were always pre-tax (Traditional). The self-employed person who wanted Roth had to use a Solo 401(k) with Roth elective deferral (which had its own administrative friction), or to contribute to a personal Roth IRA limited at $7,000.
SECURE 2.0 §601 (signed 29 December 2022, effective 1 January 2023) permitted Roth contributions inside SEP-IRA and SIMPLE IRA plans. This means a self-employed person with $200K of net SE income can now make a $40,000 Roth SEP contribution (approximately 20% of net SE income after half-SE-tax deduction), giving them roughly 5x the Roth saving capacity of a personal $7,000 Roth IRA.
Custodian implementation lagged badly. Fidelity launched Roth SEP capability in early 2024. Vanguard added it later in 2024. Schwab in 2024. Many smaller custodians did not have Roth SEP capability until late 2024 or 2025. As of 2026, the major custodians all support Roth SEP, but if you have a SEP at a smaller TPA or custodian, verify before relying on it.
The Roth SEP contribution is reported on Form 1099-R as a Code 2 distribution to the participant in the year of contribution (because the employer contribution is effectively transferred to the participant as taxable income and then re-contributed as Roth basis). The participant adds the contribution amount to their taxable income for the year. For a sole proprietor, this is a wash on the bottom line but moves the tax timing forward.
Solo 401(k) Roth and the Mega Backdoor potential
The Solo 401(k) Roth elective deferral has been available since the original Roth 401(k) provisions of EGTRRA 2001 took effect in 2006. For a self-employed person, the Roth Solo 401(k) deferral is the cleanest way to make $23,500 of Roth contributions per year directly (no backdoor, no phase-out).
The Mega Backdoor inside a Solo 401(k) works if your plan document permits after-tax employee contributions and in-plan Roth conversions. Most off-the-shelf prototype Solo 401(k) documents from Fidelity, Schwab, and Vanguard do NOT permit these. The Mega Backdoor in a Solo 401(k) requires a custom plan document, typically from a TPA specialising in self-directed retirement (Mysolo401k, Discount Solo 401(k), or MySolo401kFinancial). Setup cost is typically $200-$500 and annual maintenance is $100-$300.
The Mega Backdoor mechanics. Your Solo 401(k) plan permits employee after-tax contributions up to the $70,000 §415(c) annual addition cap. After contributing $23,500 of Roth elective deferral and $30,000 of employer profit-sharing, you have $16,500 of remaining headroom for after-tax employee contributions, which you then convert in-plan to Roth via the plan's in-plan Roth conversion feature. This adds $16,500 of Roth capacity on top of the Roth elective deferral, for a combined $40,000 of Roth saving in the Solo 401(k) alone.
For a self-employed worker earning $200K+ net SE income with a custom Solo 401(k) and a personal Roth IRA, total Roth capacity per year can exceed $50,000: $23,500 Roth elective + $16,500 Mega Backdoor + $7,000 backdoor Roth IRA = $47,000. A correspondingly W-2 worker at the same income usually has access to far less.
Choosing between SEP, Solo 401(k), and SIMPLE
If you have no employees and net SE income under $50K: SEP-IRA is the simplest. 25% of compensation (or 20% of net SE income after half-SE-tax) at $50K net is roughly $9,300 of contribution. Plus a personal Roth IRA at $7,000. Total $16,300 of tax-advantaged saving. SEP is easier than Solo 401(k) for this size.
If you have no employees and net SE income $50K to $200K: Solo 401(k) starts winning because the $23,500 elective deferral kicks in independent of compensation. A solo consultant with $80K net SE income can defer $23,500 plus roughly $14,800 employer-side (20% of $74K post-half-SE) for $38,300 total. SEP would have allowed only $14,800. Solo 401(k) gives you $23,500 more Roth capacity.
If you have no employees and net SE income above $200K: Solo 401(k) with Roth elective deferral. Consider custom plan document for Mega Backdoor if annual savings target exceeds $50K.
If you have employees: Solo 401(k) is not available (it requires owner-and-spouse-only). SEP-IRA is permitted but you must contribute the same percentage of compensation for each eligible employee. SIMPLE IRA permits employee elective deferrals up to $16,500 and a 3% employer match. For a business with 5-50 employees, the SIMPLE IRA is often the operational sweet spot. For larger businesses, a traditional 401(k) plan with safe harbour matching becomes worth the administrative cost.
The Roth-vs-Traditional decision within each vehicle
For a self-employed worker, the Roth-vs-Traditional decision is similar to a W-2 worker's decision at the same income level, with three additional considerations.
First, self-employed income varies year to year. A consultant whose income swings between $80K and $200K should make Roth contributions in low-income years (low marginal bracket) and Traditional contributions in high-income years (high marginal bracket). The annual decision can be made fresh each year because both vehicles allow either treatment.
Second, the SE tax (15.3% on the first $168,600 of net SE income in 2026) is a significant marginal cost on top of federal and state income tax. A self-employed worker at $80K net SE income has a 15.3% SE tax + 12% federal + 5% state = 32.3% marginal cost on the next dollar of income. The Traditional SEP contribution reduces federal and state income tax (deductible) but does NOT reduce SE tax (SE tax is on the SE income before the SEP deduction). The Roth SEP doesn't reduce SE tax either. Both have the same SE tax cost. The trade-off is only between federal+state income tax now vs federal+state income tax in retirement.
Third, self-employed workers do not have access to an employer 401(k) match. The standard advice to W-2 workers ("take the full match first") does not apply. The self-employed worker can move directly to the IRA / SEP / Solo 401(k) decision without a match-first layer.
FAQ
Can I do both a Roth IRA and a Roth SEP?
Yes. The personal Roth IRA at $7,000 is separate from the Roth SEP. A self-employed person can use both, subject to the standard income phase-out on the personal Roth IRA contribution. Above the phase-out, the backdoor Roth IRA is available as usual.
Is the Roth SEP-IRA available at every custodian?
Major custodians (Fidelity, Vanguard, Schwab) launched Roth SEP support in 2024. As of 2026 it is widely available. Verify with your specific custodian. Smaller TPAs may still lag.
What is the 2026 Solo 401(k) contribution limit?
$70,000 total annual addition limit. Composed of up to $23,500 employee elective deferral (Roth or pre-tax), plus up to 25% of W-2 compensation or 20% of net SE income (less half-SE-tax) as employer contribution. Age 50+ catch-up adds $7,500. Ages 60-63 super catch-up adds $11,250 instead of the regular catch-up.
Does the SEP-IRA contribution affect my SE tax?
No. The SEP contribution deduction reduces federal and state income tax but does not reduce self-employment tax. SE tax is calculated on net SE earnings before the SEP deduction. Same for Roth SEP.
What if I have employees? Can I still do a Solo 401(k)?
No. A Solo 401(k) requires that the business have only the owner and spouse as employees. If you have other employees, you need a SEP-IRA, SIMPLE IRA, or full 401(k) plan, all of which require equal treatment of eligible employees.
Is the Mega Backdoor available inside a Solo 401(k)?
Only if your plan document permits after-tax employee contributions and in-plan Roth conversion. Off-the-shelf Solo 401(k) plans from Fidelity, Schwab, and Vanguard typically do not. Custom plan documents from specialist TPAs (Mysolo401k, MySolo401kFinancial, Discount Solo 401k) do.
Not financial, tax, or legal advice. Figures sourced from IRS Notice 2024-80 (2026 limits), IRC §408(k) (SEP-IRA), IRC §401(k) (401(k) and Solo 401(k)), IRC §408(p) (SIMPLE IRA), SECURE 2.0 Act of 2022 §601 (Roth SEP and Roth SIMPLE), §604 (Roth employer match), IRC §415(c) (annual addition limit), IRC §1402 (SE tax), IRS Publication 560 (Retirement Plans for Small Business). Tax laws change. Consult a fiduciary financial advisor, CPA, or qualified retirement planner.