Ask a woman who runs her own business what she's saving for retirement, and the honest answer is usually a wince, followed by "I keep meaning to look into that." She's not lying — between the contractor payment, the sales-tax filing, and payroll for the one employee she finally hired, moving money into a retirement plan for herself starts to feel like a project reserved for some calmer month that never actually arrives. Founders who came up through corporate jobs at least had a 401(k) match landing in their account automatically, whether they thought about it or not. Solo founders don't get that nudge. Nobody is auto-enrolling a woman running a six-figure consulting practice out of her spare bedroom, so the money either goes in on purpose or it doesn't go in at all. And that gap compounds in a way that's easy to underestimate and expensive to reverse.
Why "Pay Yourself Last" Becomes "Pay Yourself Never"
The "pay yourself last" instinct that gets hammered into new founders is reasonable advice for the first eighteen months and quietly dangerous after that. Cash flow feels unpredictable even in businesses that are, on paper, doing fine — a $40,000 invoice sitting forty-five days in accounts receivable reads the same as zero dollars in the bank on a Tuesday morning, and that anxiety makes retirement contributions feel optional in a way payroll never does. Retirement savings only work if they happen on a schedule, though, and "whenever there's extra" isn't a schedule. It's a habit of deferral dressed up as prudence.
Here's the uncomfortable part: the IRS doesn't care that your Q3 was slower than Q2. Contribution limits reset every calendar year regardless of how your revenue moved, and a year with no contribution is a year of tax-advantaged room you can never claim back — there's no catch-up bucket for "I meant to in 2024." Women founders in service businesses are especially prone to this trap because revenue often tracks client relationships rather than product sales, so a single lost contract can make an entire quarter feel too fragile to commit money anywhere long-term.
Solo 401(k) vs. SEP IRA: How the Two Actually Work
Both accounts let a self-employed founder shelter income from taxes today in exchange for taxing it later, and both follow the same overall ceiling the IRS sets each year — for 2026, that combined employer-plus-employee limit is $72,000, up from $70,000 in 2025. Where they diverge is in how you're allowed to get there.
The Solo 401(k)
A Solo 401(k) (sometimes called an individual 401(k) or one-participant 401(k)) treats you as both the employee and the employer of your own business, and you get to contribute in both capacities. As the "employee," you can defer up to $24,500 of your 2026 compensation — the same limit W-2 employees get at a normal job. As the "employer," your business can then add a profit-sharing contribution of up to 25% of compensation (20% for sole proprietors and single-member LLCs, after the self-employment tax adjustment), as long as the combined total doesn't exceed that $72,000 ceiling. If you're 50 to 59 or 64 and older, add a catch-up of $8,000. If you're 60 to 63, the catch-up jumps to $11,250 under the SECURE 2.0 "super catch-up" provision, pushing the total possible contribution to $83,250.
The tradeoff is paperwork. Once your Solo 401(k) balance crosses $250,000, the IRS wants an annual Form 5500-EZ, and most providers charge a small setup or maintenance fee that a SEP IRA doesn't carry.
The SEP IRA
A SEP IRA is the account version of a shrug — open it, fund it, done. There's no employee deferral piece, only an employer contribution of up to 25% of net self-employment earnings, capped by that same $72,000 ceiling for 2026. No catch-up contributions exist for SEP IRAs regardless of age, and there's no Form 5500 filing at any balance. The simplicity is real, but so is the math problem: because you can only contribute through the employer side, you need considerably higher income to reach the same dollar amount a Solo 401(k) would let you hit. A founder who nets $90,000 can realistically max out the employee-deferral portion of a Solo 401(k) with room to spare; the same $90,000 routed into a SEP IRA caps out around $22,500. Freelance and referral-based service businesses lean toward this account for exactly that reason — the paperwork stays light even as the business itself stays lean, which matters when you're also the one doing your own bookkeeping at 9 p.m.
Which Structure Actually Fits Your Business
If you have no employees and your net self-employment income sits below roughly $150,000, take the Solo 401(k). The employee-deferral piece lets you shelter meaningful money even in a year where the business itself didn't have room for a big employer contribution, and that flexibility matters more than the extra Form 5500-EZ paperwork once your balance grows. Founders with variable, lumpy income — the ones billing project-based consulting work or running a seasonal product business — get the most out of this structure, since they can adjust the employee-deferral amount contract by contract instead of committing to a fixed percentage of pay.
Choose the SEP IRA if you've got one or two part-time contractors who might become W-2 employees, since a SEP IRA requires you to contribute the same percentage for eligible employees that you contribute for yourself — a rule that gets expensive fast once a team grows, but stays manageable and genuinely simple at very small scale. It's also the better call if you want to open and fund the account after year-end; a SEP IRA can be established as late as your tax filing deadline, including extensions, which makes it the fallback account for a founder reading this in March realizing she has nothing set up for the prior tax year. A Solo 401(k), by contrast, has to exist by December 31 of the year you want the employee deferral to count, even though you can still fund it up until your filing deadline.
Setting One Up Before the Window Closes
Fidelity, Charles Schwab, and E*TRADE all offer no-fee Solo 401(k) and SEP IRA accounts for self-employed founders, and none of them require a minimum opening balance that would meaningfully strain a small business's cash position. The paperwork itself takes maybe twenty minutes online for a SEP IRA and closer to an hour for a Solo 401(k), since the latter usually asks for a formal plan adoption agreement before the account opens. Vanguard also offers both, though its Solo 401(k) product has historically lagged the others on online account management — worth checking current reviews before committing, since brokerages update their small-business retirement tools more often than founders expect.
What actually stalls people isn't the paperwork. It's deciding how much to contribute before you've seen the whole year's numbers. The fix is simpler than it sounds: open the account now, fund it with whatever feels safe this month, and true up the rest before your filing deadline once you know your actual net income. You're allowed to contribute in pieces throughout the year rather than as one intimidating lump sum, and most self-employed founders find that monthly automatic transfers of even $500 remove the decision-fatigue entirely.
The Real Cost of Waiting
Every year you skip is a year you can't get back.
A 38-year-old founder who contributes $15,000 a year into a Solo 401(k) earning a conservative 7% average annual return will have roughly $455,000 by 60. Wait five years to start, and that number drops to around $305,000 — a $150,000 gap created almost entirely by procrastination, not by market performance or bad luck. The math doesn't punish you for contributing less in a lean year; it punishes you for contributing nothing in an average one. That distinction matters, because most founders don't skip retirement savings during genuine crises — they skip it during ordinary, forgettable quarters that felt too uncertain to commit to anything, and there were a lot of those quarters before anyone noticed how many had gone by.
A Plan You Can Actually Start This Week
Pick the account first, not the amount:
- Solo 401(k) if you're under roughly $150,000 in net income and want deferral flexibility
- SEP IRA if simplicity and a later opening deadline matter more to you right now than maximizing this year's contribution
- Either account opened this week beats the better account you're still deciding on in November — indecision has a cost too, and it's not a small one.
Open it at Fidelity or Schwab this week, before the next invoice or client fire eats the intention. Set a recurring transfer for an amount that won't touch payroll, even if that's $200 a month to start, and increase it the next time you raise your prices instead of letting a rate increase quietly disappear into the operating account. The account sitting empty does nothing for you. The one funded at $200 a month, started today, is already ahead of the one you're still planning to open in January.