401(k) glossary
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Administration
Form 5500 and Form 5500-SF
Short definition
Form 5500 is the annual report most 401(k) plans must file with the Department of Labor and IRS. It is due by the last day of the seventh month after the plan year ends, which is July 31 for calendar-year plans.
What Form 5500 is
The Form 5500 series reports a plan’s finances, participants, service providers and compliance for the year. It is filed electronically through the Department of Labor’s EFAST2 system and is public. There are three versions:
Form | Who files it |
|---|---|
Form 5500 | Large plans, generally 100 or more participants, with schedules and usually an independent audit |
Form 5500-SF | Small plans, generally fewer than 100 participants, that hold easy-to-value investments |
Form 5500-EZ | One-participant plans covering only an owner and spouse |
For 401(k) plans, the participant count for these thresholds is based on participants with account balances at the start of the plan year.
Deadlines
The form is due on the last day of the seventh month after the plan year ends. Filing Form 5558 by that date gives an extension of two and a half months, to October 15 for a calendar-year plan.
Why it matters to employers
The plan administrator signs the form under penalty of perjury, even when a provider prepares it. The form discloses late deposits and whether the plan has a fidelity bond, so it is where regulators first see problems. Late filing is costly: the IRS penalty is $250 a day up to $150,000 per return, and the Department of Labor can assess a separate penalty of up to $2,739 a day (the 2025 inflation-adjusted amount, still in effect in 2026). The Department of Labor’s Delinquent Filer Voluntary Compliance Program reduces penalties for employers that come forward.
Common mistakes
Assuming a small plan does not file. Only certain owner-only plans under $250,000 are exempt.
Missing the first-year filing for a plan that started late in the year.
Counting participants incorrectly and missing the audit requirement.
Not filing a final return when a plan terminates.
Signing without reviewing the answers on late deposits and the fidelity bond.
Basic Capital and this term
Basic Capital handles plan administration, compliance testing and Form 5500 filing.
Go deeper
Read the full employer guide related to: Form 5500 and Form 5500-SF
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Sources
Internal Revenue Service: Form 5500 corner (https://www.irs.gov/retirement-plans/form-5500-corner), retrieved 2026-11-11 U.S. Department of Labor, EBSA: Form 5500 series (https://www.dol.gov/agencies/ebsa/employers-and-advisers/plan-administration-and-compliance/reporting-and-filing/form-5500), retrieved 2026-11-11 Internal Revenue Service: About Form 5500-EZ (https://www.irs.gov/forms-pubs/about-form-5500-ez), retrieved 2026-11-11 U.S. Department of Labor, EBSA: Reporting and disclosure guide for employee benefit plans (https://www.dol.gov/sites/dolgov/files/EBSA/about-ebsa/our-activities/resource-center/publications/reporting-and-disclosure-guide-for-employee-benefit-plans.pdf), retrieved 2026-11-11
General information, not legal or tax advice.
