What is a Solo 401(k) and who qualifies?

A Solo 401(k) — also called an Individual 401(k), Self-Employed 401(k), or i401k — is a retirement plan available exclusively to self-employed individuals with no full-time employees other than a spouse. It allows contributions of up to $69,000/year ($76,500 if age 50+) through two buckets: an employee salary deferral (up to $23,000) and an employer profit-sharing contribution (up to 25% of compensation). Eligible: sole proprietors, single-member LLCs, S-corp owner-employees, and partner-only businesses. Not eligible: businesses with any non-spouse full-time employees.

How much can I contribute to a Solo 401(k) in 2026?

The 2026 Solo 401(k) contribution limit is $69,000 total, or $76,500 if you are age 50 or older. This consists of: (1) Employee deferral: up to $23,000 (or $30,500 if 50+). (2) Employer profit-sharing: up to 25% of W-2 compensation for S-corp owners, or approximately 20% of net self-employment income for sole proprietors. At income levels below ~$276,000, a Solo 401(k) allows larger total contributions than a SEP IRA because of the $23,000 employee deferral component.

What is the difference between a Solo 401(k) and a SEP IRA?

Both have the same $69,000 maximum in 2026. Key differences: Solo 401(k) advantages: allows employee salary deferrals ($23,000), which means you can contribute more at lower income levels; supports Roth contributions; allows catch-up contributions for age 50+ ($7,500 extra); allows account loans. SEP IRA advantages: simpler setup (no December 31 deadline, no Form 5500-EZ), more flexible deadline (up to October 15 with extension), can have eligible employees. Bottom line: Solo 401(k) is better for most self-employed investors under 60 who want maximum flexibility. SEP IRA wins only on simplicity for high-income investors who can max out on employer contributions alone.

What is a Roth Solo 401(k) and should I use one?

A Roth Solo 401(k) allows you to make after-tax contributions to your employee salary deferral bucket. These contributions grow tax-free and withdrawals in retirement are tax-free. Unlike a Roth IRA, a Roth Solo 401(k) has no income limit — even a self-employed person earning $500,000/year can contribute $23,000 in Roth Solo 401(k) contributions. This is one of the most powerful tools for high-earning self-employed investors. Fidelity and E*TRADE have the clearest Roth Solo 401(k) setup processes. If you're in a high tax bracket now but expect tax rates to rise, or if you want to build a tax-free retirement bucket, the Roth option is worth considering.

Can I take a loan from my Solo 401(k)?

Yes — a Solo 401(k) allows loans of up to $50,000 or 50% of your vested balance (whichever is less), repayable over up to 5 years (15 years for primary residence purchases). The interest rate is typically prime rate + 1%, and you pay the interest back to yourself. A SEP IRA does not allow loans at all. Fidelity, Schwab, and E*TRADE all support Solo 401(k) loans. Vanguard does not. Defaulting on the loan triggers income taxes plus a 10% early withdrawal penalty, so plan repayments carefully.

What is Form 5500-EZ and when do I have to file it?

Form 5500-EZ is an annual IRS information return for Solo 401(k) plans. You are required to file it when your plan's total assets exceed $250,000 at the end of the year. It's a simple one-page form — not an audit — and is due July 31 of the following year (with a 2.5-month extension available). Your broker does NOT file this for you; it's your responsibility. Below $250,000, no annual IRS filing is required. This is the one administrative burden that distinguishes a Solo 401(k) from a SEP IRA (which has no annual filing requirement).

Is Fidelity or E*TRADE better for a Solo 401(k)?

Fidelity is the better overall Solo 401(k) platform in 2026 — FZROX at 0.00% expense ratio, 4.97% APY on idle cash, $0 account fees, and 200+ branches for in-person support. E*TRADE is the better choice specifically if you want the most clearly documented Roth Solo 401(k) setup process, or if you hold equity compensation (RSUs, options) and want the Morgan Stanley research platform. Both have $0 commissions and $0 account minimums. For pure cost optimization on a large Solo 401(k) balance, Fidelity wins on fund costs by a meaningful margin over decades.

Best Brokers for Solo 401(k) 2026: Top Picks for Self-Employed Investors

Q: Do I have to open a Solo 401(k) before December 31?

Yes — for the employee salary deferral component. The Solo 401(k) plan must be established before December 31 of the tax year you want to make employee deferrals. The employer profit-sharing contribution can be made up to your tax filing deadline (April 15 or October 15 with extension). This is a critical timing difference from a SEP IRA, which can be opened and funded right up until your tax filing deadline. Mark December 31 on your calendar if you want to open a Solo 401(k) for the current tax year.

Quick Verdict — Best Solo 401(k) Brokers 2026

#1 Best Overall

Fidelity

FZROX 0.00% + Roth option + 4.97% idle cash + loans

#2 Best Branch Access

Charles Schwab

350+ branches + thinkorswim + Schwab Bank

#3 Best Roth Solo 401(k)

E*TRADE

Clearest Roth setup + Morgan Stanley research

#4 Best Index Fund Solo

Vanguard

VTI 0.03% + client-owned structure

#5 Best for Active Traders

Interactive Brokers

150+ markets + lowest margin rates + TWS

Bottom line: Fidelity is the best Solo 401(k) broker — FZROX at 0.00% expense ratio, a Roth option, plan loans, 4.97% APY on idle cash, and $0 fees. For in-person support, Schwab's 350+ branches are unmatched. For the clearest Roth Solo 401(k) process, E*TRADE is the standout.

What Is a Solo 401(k)?

A Solo 401(k) — also called an Individual 401(k) or Self-Employed 401(k) — is a retirement plan available to self-employed individuals and business owners with no full-time employees other than a spouse. It follows the same structure as an employer 401(k): you wear two hats — both employee and employer — and can contribute to both buckets.

The critical difference from a SEP IRA: the employee deferral. A Solo 401(k) lets you contribute $23,000 as the employee before the employer contribution formula even kicks in. At most income levels, this means you can shelter dramatically more money in a Solo 401(k) than in a SEP IRA at the same income.

The Two Contribution Buckets

Employee Salary Deferral

$23,000 limit+$7,500 (age 50+)Roth available

You contribute this as the "employee" of your own business. This is the key advantage over SEP IRA — a SEP IRA has no employee deferral. Must elect before Dec 31 of the contribution year.

Up to $23,000 of earned income from the business

Employer Profit-Sharing Contribution

Up to 25% of comp limit

You contribute this as the "employer" of your own business. Same formula as SEP IRA — 20% of net SE income for sole proprietors, 25% of W-2 for S-corp. Must be pre-tax (traditional) only.

20% of net self-employment income (sole prop) OR 25% of W-2 (S-corp)

Combined Total Limit

$69,000 limit$76,500 total (age 50+)Roth available

Employee + employer contributions combined cannot exceed $69,000 ($76,500 if age 50+). This is the same dollar cap as SEP IRA, but Solo 401(k) reaches it at lower income levels due to the $23,000 employee deferral.

Employee deferral + employer profit-sharing ≤ $69,000

$76,500 at Age 50+

The $7,500 catch-up contribution brings the total to $76,500 for investors 50 and older — $7,500 more than a SEP IRA can ever offer at any age.

Roth Option Available

Employee deferrals can be designated as Roth (after-tax, tax-free growth). No income limit — even $500K earners can make Roth Solo 401(k) contributions.

Loan Feature — Up to $50K

Borrow up to $50,000 or 50% of your vested balance at prime + 1%, paid back to yourself. A SEP IRA has no loan capability whatsoever.

Why Solo 401(k) Beats SEP IRA at Every Income Under $276K

At every income level below approximately $276,000, a Solo 401(k) lets you shelter more retirement money than a SEP IRA — by exactly $23,000 (the employee deferral). Both accounts use the same employer contribution formula; the Solo 401(k) just adds the $23K salary deferral on top. Only at very high incomes (where both hit the $69,000 cap) do they converge.

SE Income	SEP IRA Max	Solo Employee ($23K)	Solo Employer	Solo Total	Solo Advantage	Age 50+ Total
$40,000	$7,434	$23,000	$7,434	$30,434	+$23,000	$37,934
$60,000	$11,152	$23,000	$11,152	$34,152	+$23,000	$41,652
$80,000	$14,870	$23,000	$14,870	$37,870	+$23,000	$45,370
$100,000	$18,587	$23,000	$18,587	$41,587	+$23,000	$49,087
$150,000	$27,881	$23,000	$27,881	$50,881	+$23,000	$58,381
$200,000	$37,174	$23,000	$37,174	$60,174	+$23,000	$67,674
$276,000+	$69,000 (max)	$23,000	$46,000	$69,000 (max)	Tied at max	$76,500 (50+)

The $23,000 employee deferral is the game-changer. A self-employed person earning $60,000 can put $34,152 into a Solo 401(k) vs just $11,152 in a SEP IRA — a $23,000 difference that compounds for decades. The employer contribution formula is identical; the Solo 401(k) simply adds the $23K salary deferral on top. At higher incomes, both accounts hit the $69,000 cap, but the Solo 401(k) reaches it at a lower income threshold.

Roth Solo 401(k): More Powerful Than a Roth IRA

A Roth Solo 401(k) lets you make after-tax employee deferrals up to $23,000/year — with no income limit. This is one of the most powerful tools for high-income self-employed investors who are phased out of the Roth IRA ($146K–$161K single) but still want tax-free retirement growth.

Tax-Free Growth

Roth Solo 401(k) contributions grow completely tax-free. Unlike traditional contributions, you pay taxes now on a lower amount and never pay taxes on decades of compounding gains.

No Required Minimum Distributions

Unlike Traditional Solo 401(k), Roth Solo 401(k) accounts (once rolled to a Roth IRA) have no required minimum distributions at age 73. Your money can compound indefinitely.

Higher Roth Limits Than Roth IRA

A Roth Solo 401(k) allows $23,000/year in Roth contributions vs just $7,000/year for a Roth IRA — and there are no income limits. High earners who are phased out of Roth IRA can still use Roth Solo 401(k).

No Income Phase-Out

Roth IRA eligibility phases out at $146K–$161K (single). Roth Solo 401(k) has no income limit — a self-employed person earning $500K can still make Roth contributions of up to $23,000/year.

Roth vs Traditional Solo 401(k) — Quick Decision Guide

Choose Roth if:

You're early in your career with income expected to grow
You're phased out of Roth IRA but still want Roth growth
You believe tax rates will be higher in retirement
You want to avoid RMDs — roll to Roth IRA to eliminate them
You're building a tax-diversified retirement (some pre-tax, some Roth)

Choose Traditional if:

You're in a high tax bracket now (32%+)
You expect lower income in retirement
You want to maximize current-year tax deductions
You plan to do Roth conversions later in lower-income years
You want to reduce AGI to qualify for other deductions

Best of both worlds: Many plans allow you to split contributions — e.g., $10,000 Roth + $13,000 Traditional employee deferral in the same year, as long as total doesn't exceed $23,000. Fidelity and E*TRADE both support mixed Roth/Traditional contributions.

Top 5 Solo 401(k) Brokers (2026)

Ranked on Roth option, fund costs, plan fees, loan support, platform quality, and self-employed investor experience. Updated April 2026.

#1 PickBest Solo 401(k) Overall

Fidelity

FZROX 0.00% · Roth option · Online setup · No annual fees

4.9 / 5

Solo 401(k) Score

Fidelity is the top Solo 401(k) broker in 2026 — $0 account fees, online opening, a Roth Solo 401(k) option, and the ZERO expense ratio funds (FZROX at 0.00%) that make every dollar compound faster. The plan supports both employee salary deferrals (up to $23,000) and employer profit-sharing contributions (up to 25% of compensation) for the full $69,000 maximum. Fidelity also earns 4.97% APY on idle cash (SPAXX), critical since Solo 401(k) contributions often sit as cash between deposit and investment. Active Trader Pro is included at no cost for sophisticated self-employed traders.

Highlights

Roth Solo 401(k) option — tax-free growth for high earners

FZROX / FZILX at 0.00% — world's cheapest index funds

SPAXX earns 4.97% APY on idle contributions automatically

$0 annual account fees — no plan maintenance charge

Online opening available — plan document generated automatically

Employee + employer contributions both supported

20+ independent research providers included at no cost

200+ branches + 24/7 phone and chat support

Limitations

FZROX/FZILX non-transferable — must sell when leaving Fidelity

No futures or forex trading via Active Trader Pro

Form 5500-EZ required once balance exceeds $250,000

Open Fidelity Solo 401(k)

#2Best for Branch Access + Active Trading

Charles Schwab

350+ branches · thinkorswim platform · Schwab Bank integration

4.7 / 5

Solo 401(k) Score

Schwab is the best Solo 401(k) broker for self-employed investors who want in-person institutional support. With 350+ branches nationwide, you can discuss plan setup, contribution strategy, or estate planning in person with a financial consultant. The thinkorswim platform — 400+ indicators, paper trading, futures, options analytics — makes Schwab the top choice for self-employed active traders who also want the retirement benefits of a Solo 401(k). Schwab Bank's unlimited worldwide ATM rebates and integrated checking make cash management seamless.

Highlights

350+ physical branches — best in-person plan support

thinkorswim — 400+ indicators, paper trading, futures, forex

Schwab Bank: unlimited worldwide ATM rebates + Zelle

Roth Solo 401(k) option available

$0 annual fees, $0 commissions, $0 account minimum

Dedicated rollover and plan specialists available

Limitations

No 0.00% expense ratio fund — cheapest is SCHB at 0.03%

Fractional shares limited to S&P 500 stocks only

$50 outgoing ACAT transfer fee

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#3Best Roth Solo 401(k)

E*TRADE (Morgan Stanley)

Full Roth support · Power E*TRADE · Morgan Stanley research

4.5 / 5

Solo 401(k) Score

E*TRADE is the standout choice for self-employed investors who specifically want a Roth Solo 401(k). Their Individual 401(k) plan explicitly supports after-tax Roth contributions with a clear, well-documented setup process — making it easier to navigate than some competitors. Power E*TRADE provides options analytics, real-time scanner, and 100+ technical studies. The Morgan Stanley equity research is a genuine edge for self-employed investors managing concentrated stock positions or equity compensation. No annual plan maintenance fees.

Highlights

Best documented Roth Solo 401(k) setup process

Power E*TRADE: live action scanner, options analytics, 100+ studies

Morgan Stanley equity research at no additional cost

RSU/stock option/ESPP management — great for ex-corporate founders

$0 annual plan fees, $0 commissions

9,000+ mutual funds, 2,000+ commission-free ETFs

Limitations

No 0.00% expense ratio proprietary funds

Mobile app less polished than Fidelity or Schwab

No physical branches — fully online

Open E*TRADE Solo 401(k)

#4Best for Index Fund Solo 401(k)

Vanguard

VTI 0.03% · Client-owned · Roth option available

4.3 / 5

Solo 401(k) Score

Vanguard's Individual 401(k) is ideal for self-employed investors whose strategy is to buy VTI + VXUS and hold for decades. The client-owned structure — unique among major brokers — means fund profits are returned as lower expense ratios, not extracted by shareholders. VTI at 0.03% and VXUS at 0.07% remain the gold-standard passive funds. Vanguard does support a Roth Solo 401(k) option, and there are no annual maintenance fees for accounts over $1,000. The platform is dated but the fund economics are legendary.

Highlights

VTI at 0.03% — total US market, Vanguard's flagship ETF

VXUS at 0.07% — total international, institutional standard

Client-owned structure: fund profits flow to investors

Roth Solo 401(k) option supported

$0 commissions on all Vanguard ETFs

No maintenance fees for balances over $1,000

Limitations

Platform is genuinely dated — basic web UI only

No physical branches — online and phone only

Phone support limited to business hours (no 24/7)

Loan feature not available on Vanguard Solo 401(k)

Visit Vanguard

#5Best for Sophisticated Self-Employed Traders

Interactive Brokers

Global markets · Options expertise · Low margin rates

4.2 / 5

Solo 401(k) Score

Interactive Brokers is the best Solo 401(k) broker for sophisticated self-employed investors who trade internationally or rely heavily on options, futures, and multi-asset strategies. The IB Individual 401(k) plan supports the full $69,000 contribution limit, with Roth option available. IBKR's margin rates are the lowest in the industry (from 5.83% for large balances), and the platform provides access to 150+ global markets across 33 countries. Ideal for active self-employed traders who want retirement account benefits alongside professional-grade trading infrastructure.

Highlights

Access to 150+ global markets, 33 countries

Lowest margin rates in industry — from 5.83% on large balances

IBKR Lite: $0 commissions on US stocks and ETFs

Full options, futures, and forex capability

Roth Solo 401(k) option supported

TWS platform: professional-grade trading infrastructure

Limitations

Platform complexity overwhelms most non-traders

IBKR Pro requires per-trade commissions (not fully free)

Customer service less accessible than Fidelity or Schwab

No proprietary low-cost index funds

Open IBKR Solo 401(k)

Best Overall Solo 401(k) — 2026

Open a Fidelity Solo 401(k) Today

FZROX 0.00% · Roth option · Account loans · $0 fees · Online setup

Open Fidelity Solo 401(k)

Solo 401(k) Broker Feature Comparison

Feature	Fidelity	Schwab	E*TRADE	Vanguard	IBKR
Solo 401(k) supported	✓ Online	✓ Online	✓ Online	✓ Online	✓ Online
Account minimum	$0	$0	$0	$0	$0
Annual plan maintenance fee	$0 ✓	$0 ✓	$0 ✓	$0 (>$1,000) ✓	$0 ✓
Roth Solo 401(k) option	✓	✓	✓ (best documented)	✓	✓
Catch-up contributions (50+)	✓ +$7,500	✓ +$7,500	✓ +$7,500	✓ +$7,500	✓ +$7,500
Plan loans allowed	✓ up to $50K	✓ up to $50K	✓ up to $50K	✗ No loans	✓ up to $50K
0.00% ER index fund	FZROX 0.00% ✓	SCHB 0.03%	None	VTI 0.03%	None
Default cash yield	SPAXX 4.97% ✓	~4.5%	~4.2%	~0.01%	~4.8% ✓
Desktop trading platform	Active Trader Pro	thinkorswim ✓	Power E*TRADE ✓	Basic web only	TWS ✓
Branch locations	200+	350+ ✓	Online only	Online only	Online only
Outgoing transfer fee	$0 ✓	$50	$75	$0 ✓	$0 ✓
Mobile app quality	★★★★☆	★★★★☆	★★★★☆	★★★☆☆	★★★☆☆
International markets	US-focused	US + select intl	US-focused	US + select intl	150+ markets ✓
Research quality	★★★★★ (20+ prov)	★★★★☆ (~10 prov)	★★★★☆ (MS research)	★★★☆☆ (fund)	★★★★☆

Data as of April 2026. Verify directly with each broker before opening an account.

The Solo 401(k) Loan Feature (SEP IRA Has None)

One of the most underappreciated advantages of a Solo 401(k) over a SEP IRA: account loans. You can borrow from your own retirement account — paying the interest back to yourself — without triggering taxes or penalties. For self-employed individuals with variable cash flow, this provides a low-cost emergency credit line that doesn't depend on a bank or credit card.

Loan Terms

Maximum loan amount

Lesser of $50,000 or 50% of vested balance

Repayment period

Up to 5 years (up to 15 years if used to purchase a primary residence)

Interest rate

Prime rate + 1% — paid back to yourself

Tax consequences

No tax or penalty if repaid on schedule; default treated as distribution

Brokers Supporting Loans

Fidelity — loans supported

Schwab — loans supported

E*TRADE — loans supported

Interactive Brokers — loans supported

Vanguard — no loan feature

Best use: Business cash flow needs, emergency bridge funding, or real estate down payment — with a clear repayment plan

Solo 401(k) vs SEP IRA: 6 Scenario Verdicts

Self-employed earning $50,000 — maximize contributions

→ Solo 401(k)

At $50,000 income, SEP IRA max is ~$9,300. Solo 401(k) allows $23,000 (employee deferral) + $9,300 (employer) = $32,300 total — more than 3x the SEP IRA. The $23,000 employee deferral is available regardless of income level (as long as you have that much in earned income), making Solo 401(k) massively better for lower-to-mid-income self-employed.

Self-employed age 55 — maximize contributions with catch-up

→ Solo 401(k)

Investors age 50+ can contribute an additional $7,500 catch-up on top of the $23,000 employee deferral — bringing the total potential to $76,500/year. SEP IRA has no catch-up provision and caps at $69,000. The Solo 401(k) is the superior choice for anyone over 50 trying to accelerate retirement savings.

High earner who is phased out of Roth IRA

→ Roth Solo 401(k)

Roth IRA has an income limit — single filers phase out between $146K–$161K. A Roth Solo 401(k) has no income limit. A self-employed person earning $300,000 can still make $23,000 in Roth Solo 401(k) contributions tax-free. This is one of the most powerful Roth strategies available to high earners.

Self-employed with W-2 job + side business

→ Solo 401(k)

If you have a W-2 job and a side business, the employee deferral limit ($23,000) applies to your combined 401(k) contributions across all jobs. But the employer profit-sharing contribution from your side business is separate and additive. A SEP IRA contribution for the side business is also additive, but Solo 401(k) can still win at lower side-income levels due to the employee deferral.

Business generating emergency cash flow needs

→ Solo 401(k) with loan

Solo 401(k) is the only self-employed retirement account that allows loans. You can borrow up to $50,000 or 50% of your vested balance (whichever is less) at prime + 1% — and pay the interest back to yourself. SEP IRA has zero loan capability. For business owners who value financial flexibility, the Solo 401(k) loan feature can serve as a low-cost emergency credit line.

High-income self-employed who values simplicity above all

→ SEP IRA (not Solo 401k)

For high-income self-employed investors (earning $276,000+) who can max both accounts at $69,000, the SEP IRA wins on simplicity. Open online in 15 minutes, no December 31 deadline for employee deferrals, no Form 5500-EZ filing ever (SEP IRA is exempt). If you don't need Roth contributions, catch-up contributions, or a loan, the SEP IRA is the simpler path to the same contribution ceiling.

How to Open a Solo 401(k) — 6 Steps

Opening a Solo 401(k) is slightly more involved than a SEP IRA — the December 31 deadline for employee deferrals is the key constraint. Here's the complete setup process.

Confirm you qualify (true solo — no full-time employees)

A Solo 401(k) is available ONLY to self-employed individuals with no full-time employees other than a spouse. Eligible business structures: sole proprietors, single-member LLCs, S-corps, partnerships where all partners are spouses. If you have any non-spouse employees who work 1,000+ hours per year, you cannot use a Solo 401(k).

Open the account before December 31

Unlike a SEP IRA (which can be opened up until your tax filing deadline), a Solo 401(k) must be established before December 31 of the tax year you want to make employee deferral contributions. You can open at Fidelity or E*TRADE online. The broker will provide the plan document — no separate IRS filing is needed to establish the plan.

Decide on Traditional vs Roth employee contributions

This is a decision you make at account setup. Traditional: pre-tax now, taxed in retirement. Roth: after-tax now, completely tax-free in retirement (including growth). High earners often benefit from traditional contributions now (in a high tax bracket) and convert to Roth later. Younger self-employed investors often prefer Roth. Most plans allow both — you can split contributions.

Make employee deferral contribution (by December 31)

The employee salary deferral component (up to $23,000, or $30,500 if age 50+) must be elected and contributed by December 31 of the tax year. This is the key timing rule — miss December 31 and you lose the employee deferral for that year. You can still make employer profit-sharing contributions up to your tax filing deadline.

Make employer profit-sharing contribution (by tax deadline)

The employer contribution (20% of net SE income for sole proprietors, 25% for S-corp W-2) can be made up to your tax filing deadline — April 15 or October 15 with extension. Your CPA can finalize the exact amount once your income is settled. Total employee + employer contributions cannot exceed $69,000 ($76,500 if age 50+).

File Form 5500-EZ once balance exceeds $250,000

When your Solo 401(k) balance exceeds $250,000, the IRS requires an annual Form 5500-EZ filing. This is a simple one-page form — not a complex audit. Your broker does NOT file this for you; it's your responsibility. Below $250,000, no annual IRS filing is required. This is the only administrative burden differentiating a Solo 401(k) from a SEP IRA.

Need in-person Solo 401(k) setup guidance?

Schwab's 350+ branches offer in-person consultations for Solo 401(k) setup — contribution strategy, Roth vs Traditional decision, and plan document questions. The referral bonus may apply on new accounts.

Open a Schwab Solo 401(k)

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