Part of the Retirement Planning guide.
The main guide covers SEP IRA vs. Solo 401(k) as account structures. This is a different decision that sits inside the Solo 401(k) itself: once you’ve chosen that account, should your contributions be Traditional (pre-tax) or Roth (after-tax)?
The Core Difference
Traditional deferrals reduce your taxable income this year — you get the deduction now — and grow tax-deferred, meaning withdrawals in retirement are taxed as ordinary income.
Roth deferrals give you no deduction today, but grow completely tax-free, and qualified withdrawals in retirement owe nothing at all — not on the contributions, not on decades of growth.
Most Solo 401(k) providers let you split between both within the same plan, not just pick one exclusively.
The Freelancer-Specific Angle Most Advice Misses
Generic “Roth vs. Traditional” content is usually written for someone with a stable salary. Freelance income doesn’t work that way — and that volatility is actually an advantage here, not just a complication.
In a genuinely low-income year, lean Roth. You’re paying tax on the contribution at whatever bracket you’re in that year — if it’s a slow year, that bracket is lower than usual, making it a comparatively cheap year to prepay the tax and lock in tax-free growth afterward.
In a strong income year, lean Traditional. The deduction is worth more when it’s offsetting income taxed at a higher marginal rate. A big client project or a standout year is exactly when the current-year tax reduction from a Traditional contribution does the most work.
This is a real, year-by-year lever most W-2 employees don’t have, since their income (and therefore their bracket) doesn’t swing nearly as much.
The Part Almost Everyone Misses: Employer Contributions Are Different
Here’s a detail that surprises a lot of Solo 401(k) owners: the employer profit-sharing portion of your contribution is pre-tax by default, even if you’ve designated 100% of your employee deferral as Roth. Under SECURE 2.0, plans can now allow the employer contribution to be treated as Roth too — but this requires a specific plan feature, and most providers don’t enable it automatically.
Practically: if you defer $24,500 as Roth and your business also contributes $30,000 as employer profit-sharing, you’ll end up with $24,500 in a Roth bucket and $30,000 in a Traditional bucket, regardless of your stated preference — unless you specifically confirmed your provider supports Roth employer contributions before setting the plan up.
Where This Connects to the Rest of This Guide
This same 2026 shift toward more Roth exposure shows up elsewhere in this pillar. The new SECURE 2.0 catch-up rule, effective January 1, 2026, requires anyone age 50+ who earned over $150,000 in prior-year FICA W-2 wages to make their catch-up contributions as Roth — not optional at that income level.
Here’s the detail that matters most if you’re weighing an S-corp election alongside this decision: that $150,000 trigger is based specifically on FICA W-2 wages — Box 3 of a W-2. A sole proprietor or an unincorporated single-member LLC has no W-2 wages at all; that income runs through Schedule C and self-employment tax instead. The practical result is that an unincorporated freelancer, even one earning well past $150,000, technically falls outside this mandate entirely and retains full access to pre-tax catch-up contributions — while an S-corp owner paying themselves a W-2 salary above that threshold does not. This is a real, easy-to-miss factor worth weighing alongside everything else in the LLC vs. S-Corp guide, not just the SE tax math that guide focuses on.
And the backdoor Roth strategy covered separately in this guide exists for the same underlying reason: Roth access is becoming a deliberate default direction for higher earners looking to work around standard income limits — through a mandate for some, a workaround for others, and, for unincorporated freelancers specifically, sometimes not at all.
A Simple Framework
- Genuinely uncertain about future tax rates, or your income varies a lot year to year? Split between both — Roth in lean years, Traditional in strong ones — rather than picking one exclusively and sticking with it regardless of circumstances
- Confident you’ll be in a meaningfully lower bracket in retirement? Traditional generally wins
- Confident you’ll be in the same or higher bracket in retirement, or want guaranteed tax-free income later? Roth generally wins
- Want to confirm your specific provider supports Roth employer contributions before you rely on that feature? Ask before you set up the plan, not after your first profit-sharing contribution lands in the wrong bucket
Sources: IRC §401(k) (Roth deferral rules); SECURE 2.0 Act provisions on Roth employer contributions; 2026 Solo 401(k) contribution limits.
This article is educational content, not individualized tax or legal advice. Consult a qualified professional about your specific situation.