If you meant to open a Solo 401(k) for 2026 and didn’t get around to it, here’s the short version: the employee-deferral part of that plan is gone for this tax year, because the plan had to exist by December 31, 2026. But you haven’t lost the whole deduction. A SEP IRA can still be opened and funded for 2026 all the way up to your tax filing deadline — April 15, 2027, or October 15, 2027 if you file an extension. On $80,000 of freelance profit, that’s roughly $14,870 you can still shelter, worth about $3,271 in federal tax at the 22% marginal rate.
That’s a real rescue, not a consolation prize. The SEP IRA is the simpler, weaker cousin of the Solo 401(k) — it shelters less at the same income, and it has no Roth option and no catch-up contributions. But it is open right now, it takes about fifteen minutes to set up at any major brokerage, and it is the only self-employed retirement plan whose door is still fully open for 2026. This guide walks through exactly how much you can still save, what it costs you versus the Solo 401(k) you missed, and how to get it done before the real deadline.
The December 31 deadline that actually matters
Self-employed retirement plans don’t share one deadline. They have three different ones, and the confusion between them is exactly how freelancers lose a year of deductions.
The Solo 401(k) is the strict one. The plan itself — and your election to make employee deferrals — must be in place by December 31 of the tax year. For 2026, that was December 31, 2026. Miss it and you cannot make the $24,500 employee deferral for 2026, no matter when you file your return. The employer profit-sharing part is more forgiving: if the plan already existed by December 31, you can still make employer contributions up to your filing deadline. But if you never opened the plan at all, both buckets are closed for 2026.
The SEP IRA works the other way around. IRS Publication 560 is explicit: you can set up a SEP for any year as late as the due date of your income tax return for that year, including extensions, and you must make the contribution by that same date. For a sole proprietor filing Form 1040, that means April 15, 2027 — or October 15, 2027 if you file Form 4868 for an extension. There is no December 31 requirement at all. That single difference is the whole story of this article.
And the third plan, the SIMPLE IRA, is already gone for 2026. A SIMPLE IRA for 2026 had to be set up by October 1, 2026. If you were weighing a SIMPLE against a Solo 401(k) back in the fall and picked neither, the SIMPLE is off the table too. The SEP is the last one standing.
One more timing point worth knowing before you plan around it: the deadline that matters is the due date of your return. For most freelancers that’s April 15, 2027. If you’re an S corporation owner, your business return is due March 15, 2027 — but your SEP contribution is tied to your personal return, so the April 15 date still governs the contribution itself. Either way, don’t treat the extension date as free time. The extension only helps if you actually file Form 4868 by April 15, and contributing in October means your money sits out of the market for ten extra months.
What a SEP IRA can still shelter for 2026
The 2026 SEP IRA limit is the lesser of 25% of your compensation or $72,000, and the compensation that counts is capped at $360,000. For a sole proprietor, the math has a twist most summaries skip: the 25% applies to your compensation after the contribution itself is taken out, which works out to roughly 20% of your net earnings from self-employment — net earnings meaning your Schedule C profit minus half your self-employment tax. IRS Notice 2025-67 sets the 2026 figures, and the IRS’s own worksheet in Publication 560 walks through the circular calculation.
Here’s what that actually looks like at incomes freelancers recognize, using the Publication 560 method. These are approximations — your exact number depends on your full return — but they’re close enough to plan on:
| Schedule C net profit | Self-employment tax | SEP IRA you can still fund | Federal tax saved at 22% |
|---|---|---|---|
| $60,000 | $8,478 | $11,152 | $2,453 |
| $80,000 | $11,304 | $14,870 | $3,271 |
| $100,000 | $14,130 | $18,587 | $4,089 |
| $150,000 | $21,194 | $27,881 | $6,134 |
Two things jump out. First, even a modest freelance year shelters real money — $11,152 on $60,000 of profit is not pocket change, and the $2,453 of federal tax it saves is roughly a month of groceries for most households. Second, the SEP scales with income in a straight line. It never gives you a flat amount the way an employee deferral does, which is exactly why it loses to the Solo 401(k) at lower incomes and only catches up at very high ones. To max out a SEP at the $72,000 cap, you’d need net earnings north of $310,000.
There’s one honest limitation to put on the table before you get excited: a SEP contribution reduces your income tax, not your self-employment tax. Your Social Security and Medicare taxes are calculated on your full net earnings regardless of what you put in the SEP. That’s true of the Solo 401(k) too — neither plan touches the 15.3% — but it’s the kind of detail that turns a “I saved $6,000” claim into a “I saved $6,000 of federal income tax” claim, and the second version is the true one.
For a visual walkthrough of the same comparison, this video covers the 2026 rules with the same numbers: Solo 401(k) vs SEP IRA for Freelancers: 2026 Rules, Real Numbers.
The real cost of missing the Solo 401(k)
So what did you actually lose by missing December 31? The answer is a fixed number, and it’s worth seeing plainly, because it tells you whether the SEP rescue is “good enough” or whether you should be annoyed with yourself.
The Solo 401(k) lets you contribute as both employee and employer. The employee deferral for 2026 is $24,500 — available regardless of income, as long as you earned at least that much — plus the same employer profit-sharing contribution the SEP allows, up to the same $72,000 combined cap. At age 50 or older you can add an $8,000 catch-up; at ages 60 through 63, SECURE 2.0 raises that catch-up to $11,250.
At the same incomes as the table above, here’s the head-to-head:
| Schedule C net profit | SEP IRA only | Solo 401(k) (deferral + employer) | What you lost by missing Dec 31 |
|---|---|---|---|
| $60,000 | $11,152 | $35,652 | $24,500 |
| $80,000 | $14,870 | $39,370 | $24,500 |
| $100,000 | $18,587 | $43,087 | $24,500 |
| $150,000 | $27,881 | $52,381 | $24,500 |
The gap is the same $24,500 at every income level, because it’s exactly the employee deferral — the one bucket the SEP doesn’t have. In tax terms, at the 22% marginal rate, that’s $5,390 of federal tax savings left on the table this year. At the 24% rate it’s $5,880. That’s the price of the missed deadline, and it’s worth knowing rather than guessing at.
But notice what the table also says: the SEP still recovers the majority of the deduction at every income level. At $100,000 of profit, the SEP shelters $18,587 of the $43,087 the Solo 401(k) would have allowed — about 43%. At $150,000 it’s over half. The rescue is partial, not token. The worst move now would be to skip the SEP out of frustration over the Solo 401(k) and shelter nothing at all. A freelancer who funds the SEP in February still beats the freelancer who “waits until next year” by thousands of dollars, and the money goes into the same kind of tax-deferred account either way.
If you already have a Solo 401(k) open from a previous year, by the way, none of this applies to you in the same way — your plan existed before December 31, so your 2026 deferral election just needed to be made by then, and your employer contribution can still be funded up to your filing deadline. The rescue in this article is for people who never opened one.
How to open and fund a SEP IRA before April 15, 2027
This is the easy part. A SEP IRA is the simplest retirement account in the tax code to open, and that’s not marketing language — there’s no plan document to draft, no annual IRS filing, and no setup fee at the big brokerages.
1. Pick a custodian. Fidelity, Schwab, and Vanguard all offer SEP IRAs with no annual fees and no minimums. If you already have a brokerage account somewhere, open it there — having your retirement money next to your existing investments makes the contribution step trivial. Any of the three works fine; don’t burn a week comparison-shopping custodians over a decision that barely matters.
2. Open the account as a SEP IRA, not a traditional IRA. This is the one step people get wrong. A SEP IRA looks like a traditional IRA once it’s open, but it has to be established as a SEP — the custodian files Form 5305-SEP for you, and that form is what makes the higher contribution limit legal. If you accidentally open a regular IRA and stuff $14,000 into it, you’ve made an excess contribution, not a SEP contribution. Check the account type on the confirmation screen before you fund it.
3. Calculate your contribution. Use the IRS worksheet in Publication 560, or your custodian’s SEP calculator, or — most reliably — ask your tax preparer to run the number when they do your return. The contribution is based on your actual 2026 net earnings, which you won’t know precisely until your Schedule C is done. If you fund it early in the year with an estimate, keep a small cushion: you can always top it up before April 15, but an excess contribution is a headache to unwind.
4. Fund it before the deadline. The money has to be in the account by April 15, 2027 (or October 15, 2027 with a filed extension). A transfer initiated on April 14 that settles on April 16 is late. Don’t cut it that close — fund it by early April at the latest, and if you’re filing an extension, remember the extension has to be filed by April 15 too.
5. Claim it on your return. SEP contributions for a sole proprietor go on Schedule 1, line 16 of Form 1040 (the self-employed SEP, SIMPLE, and qualified plans line). Your custodian won’t send you a special form for it the way a W-2 employer would — you report it yourself, and you keep the Form 5305-SEP and your contribution records in case the IRS ever asks.
6. Invest it, don’t park it. The money sitting in the SEP’s settlement fund earns money-market interest and nothing more. Pick a low-cost target-date fund or a simple three-fund mix and set it up the same day you fund the account. The tax deduction is the headline, but the compounding over the next twenty or thirty years is the real prize.
One timing tip from the trenches: if your 2026 income is still coming in — late invoices, a 1099 that hasn’t arrived — wait until your books are final before funding the full amount. You can open the account in January and fund it in March. The deadline rewards accuracy, not speed.
The traps nobody mentions until it’s too late
The SEP IRA’s simplicity comes with fine print, and three of these items bite freelancers specifically.
If you have employees, the SEP covers them too. This is the big one. A SEP IRA requires you to contribute the same percentage of compensation for every eligible employee as you contribute for yourself. Eligible generally means age 21 or older, worked for you in at least three of the last five years, and earned at least $750 in the year. If you’re a true solo freelancer, this doesn’t matter. But if you hired a part-time assistant in 2024 who stuck around, funding your own SEP at 20% means funding theirs at 20% too. The Solo 401(k) doesn’t have this problem — it’s only available to businesses with no employees other than a spouse, which is exactly why the two plans fit different businesses. If you’ve got employees, talk to a CPA before funding a SEP; the employee cost can dwarf your own deduction.
S corporation owners play by different rules. If your business is an S corp, your SEP contribution is based on your W-2 wages from the corporation, not on the business’s profit — and only wages that were actually paid count. Your Solo 401(k) deferral, had you opened one, would also have had to come out of W-2 wages through payroll by December 31. The SEP rescue still works for S corp owners, but the contribution math runs off your salary, so a low salary means a small SEP. This is one of the real trade-offs of the S corp salary-vs-distribution strategy: every dollar you didn’t take as salary is a dollar that can’t go into a SEP.
No Roth, no catch-up, no loans. A SEP IRA is pre-tax only. SECURE 2.0 technically authorized Roth SEP contributions, but as of 2026 very few custodians actually offer them, so plan on pre-tax. There are no catch-up contributions at age 50+, unlike the Solo 401(k)’s $8,000 (or $11,250 at ages 60–63). And you can’t borrow from a SEP the way some Solo 401(k) plans allow loans of up to 50% of the balance or $50,000, whichever is less. None of these is a reason to skip the SEP for 2026 — they’re reasons to set up the Solo 401(k) for 2027.
The paperwork is light, but not zero. A SEP IRA has no annual IRS filing, which is a genuine advantage over a Solo 401(k) — the Solo 401(k) requires Form 5500-EZ once plan assets exceed $250,000. But you still need to keep the Form 5305-SEP and your contribution records. And if your business is a partnership or corporation rather than a sole proprietorship, the deadlines and the compensation definitions shift — the April 15 date in this article is for the individual return, and entity returns have their own calendars.
And a final note on the tax bracket math in this article: the 22% figures assume a single filer in the 22% bracket. Your actual marginal rate depends on your total income, and the 2027 tax brackets and standard deduction figures are worth checking when you run your own numbers. The SEP deduction is worth the most in exactly the years your income spikes — a big project year, a windfall client — because that’s when your marginal rate is highest.
What to do differently for 2027
The SEP fixes 2026. It doesn’t fix the habit that caused the problem, and the Solo 401(k) is still the better plan for most solo freelancers — the $24,500 deferral is simply too valuable to leave on the table twice.
So put this on your calendar now, not next December: open a Solo 401(k) before December 31, 2027. You don’t need to fund it in 2027 to preserve the option — you need the plan to exist and the deferral election to be made by year-end. You can fund the deferral and the employer contribution in early 2028, up to your filing deadline, just like the SEP. The only thing that has to happen in 2027 is the paperwork.
If you want the best of both worlds, you can actually hold both accounts: fund the SEP for 2026 now, and open the Solo 401(k) for 2027. The IRS allows you to maintain both, though the combined contributions across plans still can’t exceed the $72,000 overall limit for the year, and the SEP’s employee-coverage rule still applies if you have staff. For a solo freelancer, running the SEP for the rescue year and the Solo 401(k) going forward is the cleanest path.
There’s also a small sweetener worth knowing about: a Solo 401(k) may qualify for a tax credit of up to $500 a year for three years for startup costs, claimed on Form 8881 under the SECURE Act. SEP IRAs don’t qualify. It’s not a reason to choose a plan on its own, but it’s one more small edge for getting the Solo 401(k) open this year instead of next.
And if you haven’t sorted out the rest of your freelance tax year yet — the 1099-NEC threshold for 2026 is now $2,000, up from $600 — it’s worth a look while your books are open anyway. The same return that carries your SEP deduction is the one where those thresholds matter.
The bottom line is simple: December 31 cost you $24,500 of contribution room for 2026, and that’s annoying, but it didn’t cost you the whole year. A SEP IRA opened before April 15, 2027 still shelters up to $72,000, still cuts your federal tax bill by thousands, and still takes fifteen minutes to set up. Fund it, then set a reminder for November 2027 to open the Solo 401(k). Future you — the one retiring on the money — will be glad you did both.
This article is educational, not professional tax advice. Retirement plan rules depend on your business structure and full tax picture — check the current IRS rules and talk to a qualified tax professional before contributing.
Frequently Asked Questions
Can I open a SEP IRA for 2026 after December 31, 2026?
Yes. Unlike a Solo 401(k), which must be established by December 31 of the tax year, a SEP IRA can be opened and funded up until your tax filing deadline — April 15, 2027 for most freelancers, or October 15, 2027 if you file an extension. The contribution must be in the account by that date.
How much can I contribute to a SEP IRA for 2026?
The lesser of 25% of your compensation or $72,000. For a sole proprietor, the 25% works out to roughly 20% of net earnings from self-employment (your Schedule C profit minus half your self-employment tax), because the contribution itself reduces the compensation base. On $80,000 of net profit, that’s about $14,870.
I already missed the Solo 401(k) deadline — is the SEP IRA my only option left?
For 2026, effectively yes. The SIMPLE IRA setup deadline was October 1, 2026, so that’s closed too. The SEP IRA is the only self-employed plan that can still be opened and funded for 2026. A traditional or Roth IRA is still available until April 15, 2027 as well, but its limit is only $7,500 for 2026.
Does a SEP IRA contribution reduce my self-employment tax?
No. SEP contributions reduce your federal income tax only. Your Social Security and Medicare taxes are calculated on your full net earnings from self-employment, regardless of what you contribute. The same is true of Solo 401(k) contributions.
Can I have both a SEP IRA and a Solo 401(k)?
Yes, you can maintain both accounts, but your combined contributions across plans for the same year can’t exceed the overall $72,000 limit (plus catch-ups where applicable). A common approach is to fund the SEP for the rescue year and open a Solo 401(k) for the following year.
What happens if I contribute too much to my SEP IRA?
An excess SEP contribution must be removed, with earnings, by your filing deadline (including extensions) to avoid a 6% excise tax for each year it remains in the account. That’s why it’s worth calculating the number from your finished Schedule C rather than guessing early in the year.