The filing requirement most solo 401(k) owners never hear about
Form 5500-EZ is the annual return for one-participant retirement plans — solo 401(k)s covering only a business owner (and spouse) or partners (and their spouses). Two triggers create the duty to file:
- The $250,000 threshold: total assets across your one-participant plans exceed $250,000 on the last day of the plan year.
- The final-year rule: the year a plan terminates and distributes all assets, a final return is required regardless of balance — even a $61,000 plan owes a final 5500-EZ.
The due date is the last day of the seventh month after the plan year ends — July 31 for calendar-year plans. Form 5558, filed by July 31, buys an automatic extension to October 15.
Why so many people miss it: contributions take years to cross $250,000, but a single rollover — say, moving an old IRA into the solo 401(k) as step one of a backdoor Roth — can blow past the threshold overnight. And your custodian does not file this for you. When the IRS sampled one-participant plan filers, most sponsors contacted had missed at least one 5500-EZ.
The $500 fix: Rev. Proc. 2015-32, step by step
The IRS maintains a permanent penalty relief program for one-participant and foreign plans. Instead of $250/day, you pay a flat $500 per delinquent return, capped at $1,500 per plan no matter how many years you missed — so filing multiple late years together is the money move.
- Confirm you actually owed the filing. Assets over $250,000 at year-end, or a final-year return? If your plan held $180,000 and isn't terminating, you had no duty — stop here.
- Prepare a complete paper Form 5500-EZ for each delinquent year, using that year's form.
- Check Box D in Part I ("IRS Late Filer Penalty Relief Program"). For pre-2020 forms without Box D, write "Delinquent Return Filed under Rev. Proc. 2015-32, Eligible for Penalty Relief" in red at the top — miss this and the submission can be ineligible.
- Attach Form 14704 (the transmittal schedule) to the front of the oldest return in the submission.
- Include the fee: $500 per return, max $1,500 per plan, check payable to "United States Treasury."
- Mail on paper to the IRS in Ogden, UT (1973 Rulon White Blvd., Ogden, UT 84201). Electronically filed EFAST2 returns are not eligible for this relief. Send certified mail and keep everything.
Two disqualifiers: (1) you already received a CP 283 for that year, or (2) your plan covers any employee beyond owners and spouses — that makes it an ERISA Title I plan, which uses the Department of Labor's DFVCP instead. Note: 2%+ S corporation shareholders are treated like partners for the one-participant test.
Already got the CP 283? Reasonable cause is the remaining path
Once the penalty is assessed, Rev. Proc. 2015-32 is off the table for that year — but the penalty is still fightable. The standard is reasonable cause: you exercised ordinary business care and prudence and still couldn't comply. Documented serious illness, death in the family, disaster, or records you genuinely couldn't obtain are the classic fact patterns. Respond within the notice deadline with a signed statement and evidence; if denied, you can take it to the IRS Independent Office of Appeals.
Romeo Razi, CPA — Former IRS Auditor
"I've watched five-figure 5500-EZ penalties get assessed against people whose only mistake was a rollover they didn't know crossed a threshold. Here's the pattern that matters: the IRS's own program forgives almost everything for $500 a year — but only until the CP 283 lands. The single most expensive thing you can do is let mail from Ogden sit unopened. If you're behind, file under the relief program this week, not after the IRS writes first. And when a penalty is abated, remember the interest that accrued on it comes off too."
Related reading: our full guide to IRS penalty abatement and reasonable cause, the new Automatic Exemption from Penalty (AEP) program (note: AEP covers income and employment tax returns — it does not cover Form 5500-EZ, an information return), and what to do about IRS balance-due notices. If penalties have already snowballed into a balance you can't pay, see installment agreements and Currently Not Collectible status.
Sources, and how this guide was researched
This guide was written by Romeo Razi, CPA, a former IRS Tax Examiner who has represented one-participant plan sponsors through both the Rev. Proc. 2015-32 relief program and post-CP 283 reasonable cause abatements. The figures, notice sequence, and program mechanics come from the IRS primary sources below:
Every figure and deadline above was checked against these primary sources at the time of writing, not against secondary coverage. Tax rules change; before acting on a deadline or dollar amount, confirm the current version at the linked source or ask us directly.
Frequently asked questions
Who has to file Form 5500-EZ?
One-participant retirement plans — a solo 401(k) or similar plan covering only a business owner (and spouse), or partners (and their spouses), with no common-law employees. You must file for any year the plan's total assets exceed $250,000 on the last day of the plan year, and you must always file a final return in the year the plan terminates and distributes all assets, regardless of the balance.
When is Form 5500-EZ due?
The last day of the seventh month after the plan year ends — July 31 for calendar-year plans. You can extend to October 15 by filing Form 5558 by July 31. Miss July 31 without an extension and you're delinquent on day one, with the $250-per-day clock running.
What is the penalty for filing Form 5500-EZ late?
$250 per day, up to $150,000 per late return, plus interest, under IRC Section 6652(e) as amended by the SECURE Act (a tenfold increase from the old $25/day, $15,000 cap). You hit the $150,000 maximum after just 600 days, and the plan administrator — you personally — is liable. Three missed years can theoretically stack to $450,000.
What is the $500 fix for a late 5500-EZ?
The IRS Penalty Relief Program under Revenue Procedure 2015-32: file the delinquent returns on paper with Form 14704 attached and pay a flat $500 per late return, capped at $1,500 per plan no matter how many years you missed. The IRS waives the daily penalty entirely. It's a permanent program, not a one-time amnesty.
How do I file under Rev. Proc. 2015-32 step by step?
(1) Prepare a complete paper Form 5500-EZ for each delinquent year. (2) Check Box D in Part I ('IRS Late Filer Penalty Relief Program'); for pre-2020 form years without Box D, write 'Delinquent Return Filed under Rev. Proc. 2015-32, Eligible for Penalty Relief' in red at the top. (3) Attach Form 14704 to the front of the submission. (4) Include a check for $500 per return (max $1,500 per plan) payable to United States Treasury. (5) Mail to the IRS in Ogden, UT — electronic EFAST2 filings are NOT eligible. Keep certified-mail proof.
What if I already received a CP 283 penalty notice?
Then the $500 program is closed for that year — Rev. Proc. 2015-32 is only available before the IRS assesses the penalty. Your remaining path is reasonable cause abatement: respond to the CP 283 within the deadline with a documented explanation (serious illness, disaster, records you couldn't obtain despite ordinary business care). If denied, you can appeal to the IRS Independent Office of Appeals. This is exactly the kind of case a former IRS auditor handles.
What notices does the IRS send for a missing 5500-EZ?
Roughly 15 months after the due date you may get a CP 403 delinquency notice — by which point the daily penalty math already sits around $112,500. If you don't respond in 30 days, a CP 406 final notice follows about 15 weeks later. If the IRS then assesses, you receive CP 283 (Penalty Charged on Your Form 5500 Return) — and the cheap $500 door closes for that year. Never let mail from Ogden sit unopened.
I never filed because I didn't know my solo 401(k) crossed $250,000 — am I alone?
Not remotely. The IRS sampled one-participant plan filers and found most sponsors contacted had missed at least one Form 5500-EZ. The classic trigger is a rollover: moving an old IRA or 401(k) into your solo 401(k) — a common step in backdoor Roth planning — can push the balance over $250,000 overnight. And no, your custodian (Fidelity, Schwab, Vanguard) does not file this for you; the responsibility is yours as plan administrator.
Does the relief program cover plans with employees?
No. The moment a plan covers any employee beyond the owners and their spouses, it's an ERISA Title I plan and uses the Department of Labor's Delinquent Filer Voluntary Compliance Program (DFVCP) instead. Note that S corporation shareholders owning 2%+ are treated like partners for the one-participant test.
Do I even owe a filing? How do I check before paying $500?
Verify two things first: (1) did combined assets across all your one-participant plans exceed $250,000 on the last day of the plan year, and (2) is this the plan's final year (final-year returns are required at ANY balance)? If your solo 401(k) held $180,000 at year-end and it isn't the final year, you had no filing duty — don't pay a relief fee you don't owe.
By Romeo Razi, CPA — Former IRS Tax Examiner
·Published July 14, 2026
·Fact-checked against IRS primary sources