Updated October 1, 2026. Quick answer: A one-participant retirement plan, such as a solo 401(k) that covers only the owner or the owner and spouse, files Form 5500-EZ once its assets pass $250,000. The test counts the plan’s assets at the end of the plan year together with every other one-participant plan the employer maintains. At or below $250,000 no return is required, unless it is the plan’s final year. The return is due the last day of the seventh month after the plan year ends, and the penalty for missing it is $250 a day up to $150,000.
S corporation return (Form 1120-S) for 2025, read line by line: Form 1120-S lines 13 to 22.
Partnership return (Form 1065) for 2025, read line by line: Form 1065 lines 15 to 18 and Form 1065 lines 19 to 23.
More IRS forms and schedules, read line by line: Form 5330 instructions.
Who files Form 5500-EZ
The IRS instructions say: “You must file Form 5500-EZ for a retirement plan if the plan is a one-participant plan or a foreign plan that is required to file an annual return under section 6058(a).” A one-participant plan is one that “Covers only you (or you and your spouse) and you (or you and your spouse) own the entire business (which may be incorporated or unincorporated); or” “Covers only one or more partners (or partners and their spouses) in a business partnership”.
Hiring an employee who is covered changes the form: “A one-participant plan must file an annual return unless the plan meets the conditions for not filing under Who Does Not Have To File Form 5500-EZ below.” A plan that is not eligible for Form 5500-EZ files the Form 5500 or Form 5500-SF; see the Form 5500-SF versus full Form 5500 page.
The $250,000 test
The filing threshold is an asset test: “You do not have to file Form 5500-EZ for the 2025 plan year for a one-participant plan if the total of the plan’s assets and the assets of all other one-participant plans maintained by the employer at the end of the 2025 plan year does not exceed $250,000, unless 2025 is the final plan year of the plan.”
The measure is specific: “You should use the total plan assets as listed as of the end of the plan year on line 6a(2) of this form to determine whether the plan(s) assets exceed $250,000.” And once it is crossed, the filing applies to every plan: “Form 5500-EZ must be filed for each of the employer’s one-participant plans including those with less than $250,000 in assets for the 2025 plan year.”
| Example (computed here, plan year-end assets) | Total counted | Form 5500-EZ required |
|---|---|---|
| One plan, $180,000 at year-end | $180,000 | No, unless it is the final plan year |
| One plan, $260,000 at year-end | $260,000 | Yes |
| Two plans, $140,000 and $120,000 | $260,000 | Yes, a return for each of the two plans |
The examples are arithmetic on the $250,000 line in the instructions, not IRS examples, and they assume no other one-participant plan and that the year is not the plan’s last.
The final plan year
The asset exception does not apply in the plan’s last year: “All one-participant plans and all foreign plans should file a return for their final plan year indicating that all assets have been distributed.”
Due date and extension
The date is the same seventh-month rule as the larger form: “Form 5500-EZ must be filed by the last day of the 7th calendar month after the end of the plan year that began in 2025 (not to exceed 12 months in length).” That is July 31 for a calendar-year plan. An extension is available: “A one-time extension of time to file Form 5500-EZ (up to 2½ months) may be obtained by filing Form 5558 on or before the normal due date (not including any extensions) of the return.” Each plan needs its own request: “A separate Form 5558 must be used for each plan for which an extension is requested.” Details are on the Form 5500 due date page.
Paper or electronic
Paper is allowed for many filers: “The 2025 Form 5500-EZ may be filed on paper.” There is a mandatory electronic rule for frequent filers: “A filer must file the Form 5500-EZ electronically using the EFAST2 Filing System for plan year beginning on or after January 1, 2025 if the filer is required to file at least 10 returns of any type with the IRS”, counting information returns such as Forms W-2 and 1099. “If a filer is required to file a Form 5500-EZ electronically but does not, the filer is considered to have not filed the form even if a paper Form 5500-EZ is submitted.”
Schedules, privacy and the penalty
The form is short: “Filers of Form 5500-EZ are not required to file schedules or attachments related to Form 5500 with the 2025 Form 5500-EZ.” The filing is not published online: “the information for a one-participant plan or a foreign plan, whether filed electronically with EFAST2 or filed on paper, will not be published on the internet.”
The penalty: “Code section 6652(e) imposes a penalty of $250 a day (up to a maximum penalty of $150,000 per plan year) for not filing returns in connection with pension, profit-sharing, etc., plans by the required due date.”
Common mistakes
- Testing each solo plan against $250,000 separately. The employer’s one-participant plans count together.
- Skipping the return in the year the plan is closed out. The final year is always reported.
- Mailing a paper return when the owner files ten or more other returns with the IRS in the year.
Related: the solo 401(k) contribution limit, a solo 401(k) with employees, the Form 5500 instructions, and the Form 5500 due date.
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Answer againSources
- IRS Instructions for Form 5500-EZ (2025): https://www.irs.gov/pub/irs-pdf/i5500ez.pdf
- IRS Form 5558 (Rev. January 2025), Application for Extension of Time To File Certain Employee Plan Returns: https://www.irs.gov/pub/irs-pdf/f5558.pdf
Read from the DOL, IRS and PBGC documents linked above on October 1, 2026. General information, not tax advice. Your own facts decide the outcome, and a preparer, the account provider or the IRS is the right place to confirm anything consequential.