Roth vs. Traditional Solo 401(k): Which Should Freelancers Choose?

Every solo 401(k) provider asks this on the setup screen, usually as a radio button with no explanation attached. Traditional, or Roth. Most freelancers click one in about four seconds and never revisit it, which is unfortunate, because on a decade of contributions the gap between the right answer and the wrong one runs into five figures.

The good news is that the decision has one real input. Everything else is a tiebreaker.

The question that actually decides it

Both accounts shelter investment growth from tax. The only difference is when the IRS collects. A traditional deferral is deducted from your income now and taxed when you withdraw it. A Roth deferral is taxed now and comes out tax-free later, assuming the account is at least five years old and you are past 59 and a half.

So the comparison is: what rate would you pay on this dollar in 2026, and what rate do you expect to pay on it in retirement? Higher now, take the deduction. Higher later, pay the tax now and take the Roth. Identical, and the two are a wash before tiebreakers.

The mistake is in how people estimate the first number. They look up their bracket, see 22%, and assume the deduction is worth 22 cents. For a self-employed person it usually is not.

What each one does to this year's return

The 2026 employee deferral limit is $24,500 either way, per IRS Notice 2025-67. Add $8,000 if you turn 50 or older this year, or $11,250 instead if you turn 60, 61, 62 or 63. Employee plus employer contributions together cap at $72,000.

The deduction is worth less than your bracket says

Here is the piece almost nobody accounts for. A traditional deferral lowers your taxable income, and a lower taxable income means a smaller qualified business income deduction, because that deduction is 20% of a number the deferral just shrank. You give some of the saving back on the way out.

Tomas is in the 22% bracket. His deduction is worth 14.1%. Two things pulled it down. The QBI deduction gave back a fifth of the benefit, since a $18,000 deferral only lowered taxable income by $14,400. And of that $14,400, just $8,094 came out of the 22% bracket. The other $6,306 came out of the 12% band, where a deduction saves 10 cents less on every dollar.

That number matters, because it sets the real break-even. Tomas is not asking whether his retirement rate will be above 22%. He is asking whether it will be above 14.1%. That is a much lower bar, and it changes the answer for a lot of people.

Where the same $18,000 lands in 25 years

Run both versions forward. At 7% a year for 25 years, $18,000 grows to about $97,694 in either account. What differs is who owns it at the end.

That is the whole result in one line: the break-even is whatever the deduction is actually worth this year, and for Tomas that is 14 cents rather than 22. Two things bend it further toward Roth. The side account is a taxable brokerage account, so it loses a slice to tax along the way that the calculation above ignores. And most people do not invest the saving at all. If you know you will spend it, the traditional side has to win on the withdrawal rate alone, which is a much harder ask.

There is also a quieter advantage on the Roth side. The limit is $24,500 of contributions, not $24,500 of after-tax value. Maxing the Roth bucket puts $24,500 of already-taxed money into the account. Maxing the traditional bucket puts in $24,500 that still owes tax. For anyone trying to get as much as possible into a tax-sheltered account, Roth quietly holds more.

Five tiebreakers when the rates look close

1. The 2026 Roth catch-up rule probably does not touch you

Starting this year, a participant whose prior-year FICA wages from the plan sponsor exceeded $150,000 has to make catch-up contributions as Roth. Freelancers have been asking whether that forces their hand. For a sole proprietor, it does not. The final catch-up regulations published in the Federal Register on Sept. 16, 2025, confirm that someone with no FICA wages from the sponsoring employer, including a self-employed individual or a partner with only self-employment income, is not subject to the requirement. Schedule C profit is not FICA wages. If you also run payroll for yourself through an S corporation, check the W-2.

2. Roth accounts have no lifetime required distributions

Under section 325 of the SECURE 2.0 Act, designated Roth accounts in a 401(k) stopped being subject to required minimum distributions during the owner's lifetime starting in 2024. Traditional balances still force withdrawals in your 70s whether you need the money or not, which can push you into a higher bracket in a year you did not plan for. Heirs still face distribution rules either way.

3. Lumpy income is a reason to alternate, not to pick once

This is the freelancer-specific point. A salaried person has roughly the same bracket every year. You do not. A year where a big client left and profit came in at $38,000 is a cheap year to pay tax, so route the deferral to Roth. A year where profit hit $160,000 is an expensive year, so take the deduction. The choice is annual, and treating it as a one-time setting throws away the one advantage variable income actually gives you.

4. The employer contribution is a separate decision

Your profit-sharing contribution, the employer side, has historically been pretax only. Section 604 of the SECURE 2.0 Act lets plans offer it as Roth, but the plan document has to allow it, and plenty of solo 401(k) providers still do not. If yours does, the contribution is includible in your income for the year it is allocated and gets reported on a Form 1099-R with code G in box 7. Ask your provider before assuming the option exists. Our guide to the two contribution buckets covers how the employer number is calculated.

5. Neither one touches self-employment tax

Worth repeating because it is the most common misunderstanding on this site. Self-employment tax is charged on net profit before any retirement contribution. A $24,500 deferral of either flavor leaves your SE tax bill exactly where it was. Business expenses reduce that base. Retirement contributions do not.

What to do before Dec. 31

Three steps, in order, and the deadline is real. The election to defer has to be on file with your plan by the end of the year even though the money itself can go in as late as your filing deadline. Providers set their own earlier cutoffs, so December 31 is the outside edge, not the target.

First, project your full-year profit. You have nine months of real numbers, so this is arithmetic now rather than forecasting. Second, find the rate the deduction would actually save you, which means running your taxable income with and without the deferral and watching what happens to the QBI line. Skip that step and you will overestimate the traditional side by a third or more. Third, compare that number to the rate you expect in retirement and pick accordingly, or split if the two are close enough that you would rather not guess.

One more thing that costs nothing: write down what you picked and why, somewhere you will actually find it next November. Your profit will be a different number in 2027, and the answer may well flip. This is a question worth reopening every December rather than a switch you set once in the account you opened years ago.