401(k) Audit Deadline: Form 5500 Due Dates and Extensions
Form 5500 due dates, the Form 5558 extension, what happens when the audit is not ready, and how the Delinquent Filer Voluntary Compliance Program limits penalties.
Last updated · Source data: plan year 2024 Form 5500 filings
When is a 401(k) audit due?
The audit report is due with Form 5500: the last day of the seventh month after the plan year ends — July 31 for calendar-year plans. Filing Form 5558 by that date extends the deadline 2½ months, to October 15. There is no separate audit deadline or second extension.
The rule: the audit is due with Form 5500
ERISA Section 103 requires a large plan’s annual report to include the opinion of an independent qualified public accountant (IQPA). That opinion, with the audited financial statements and ERISA supplemental schedules, is attached to the plan’s electronic Form 5500; Schedule H, line 3 identifies the accountant and the type of opinion issued. There is no separate audit filing and no separate audit due date.
Under 29 CFR 2520.104a-5(a)(2), Form 5500 is due by the last day of the seventh calendar month after the close of the plan year. For a calendar-year plan that is July 31; for a plan year ending June 30 it is January 31. If the due date falls on a Saturday, Sunday, or federal holiday, the filing may be made on the next business day. Filing is electronic only, through EFAST2, and a large-plan filing submitted without the required accountant’s report is incomplete.
Form 5500 and audit deadlines by plan-year end
| Plan year ends | Form 5500 and audit due | Extended due date (Form 5558) |
|---|---|---|
| December 31 (calendar year) | July 31 | October 15 |
| January 31 | August 31 | November 15 |
| February 28 / 29 | September 30 | December 15 |
| March 31 | October 31 | January 15 |
| April 30 | November 30 | February 15 |
| May 31 | December 31 | March 15 |
| June 30 | January 31 | April 15 |
| July 31 | February 28 / 29 | May 15 |
| August 31 | March 31 | June 15 |
| September 30 | April 30 | July 15 |
| October 31 | May 31 | August 15 |
| November 30 | June 30 | September 15 |
Normal due date: last day of the seventh month after the plan year ends. Extended date: the 15th day of the third month after the normal due date (2½ months). Dates falling on a weekend or federal holiday roll to the next business day.
What extensions exist for a 401(k) audit?
| Route | Extra time | Conditions |
|---|---|---|
| Form 5558 (Application for Extension of Time) | 2½ months — to the 15th day of the 3rd month after the normal due date | Must be filed on or before the normal due date. Automatic; no IRS approval letter is issued and no signature is required for the Form 5500 extension. Since January 1, 2025 it can be filed electronically through EFAST2; paper filing with the IRS remains available. The same form extends Form 8955-SSA. |
| Automatic extension with the sponsor’s federal income tax extension | To the extended due date of the employer’s income tax return | Available only when the plan year and the employer’s tax year are the same and the employer obtained a tax-return extension to a date later than the normal Form 5500 due date. Keep a copy of the extension with the plan’s records. For calendar-year partnerships and S corporations that date is September 15 — earlier than Form 5558. |
| Federally declared disaster relief | To the postponement date announced by the IRS | The Department of Labor and PBGC generally adopt IRS disaster postponements for Form 5500 filings by affected plans. Relief is announced per event; it is not automatic for everyone. |
| Short plan year audit deferral (29 CFR 2520.104-50) | Audit only — one year | A plan year of seven months or fewer may defer its audit: the short-year Form 5500 is filed on time without the accountant’s report, and the next year’s filing attaches one audit covering both periods. The filing deadline itself does not move. |
| A second extension | None | The 2½-month Form 5558 extension is the maximum. There is no further extension for an unfinished audit. |
What if the audit is not finished by the deadline?
- Before the normal due date: file Form 5558. It is automatic, costs nothing, and buys 2½ months. Most plans that will need the time should file it in July rather than gamble on fieldwork finishing early.
- After the extended date: file the complete return — audit report included — as soon as it is ready, and pay the reduced penalty under the Delinquent Filer Voluntary Compliance Program (DFVCP) before the Department of Labor writes to you. A DFVCP filing for a large plan costs at most $2,000 per year; a DOL penalty assessment has no cap.
- Filing without the report: the DOL treats a large-plan filing that lacks the IQPA’s report as deficient under 29 CFR 2560.502c-2. EBSA’s Office of the Chief Accountant typically sends a notice allowing 45 days to correct; an uncorrected filing is rejected and penalties can run as if nothing had been filed. Written DOL notice also closes the door to DFVCP.
Penalties for a late or incomplete Form 5500
| Penalty | Amount | Cap | Authority |
|---|---|---|---|
| DOL: late, incomplete, or rejected annual report | Up to $2,739 per day (2025 amount, inflation-adjusted each January) | No maximum | ERISA §502(c)(2); 29 CFR 2575 |
| IRS: late Form 5500 | $250 per day | $150,000 per plan year | IRC §6652(e), as amended by the SECURE Act |
| IRS: late Form 8955-SSA | $10 per participant per day | $50,000 | IRC §6652(d)(1) |
| DFVCP: small plan (fewer than 100 participants) | $10 per day | $750 per filing; $1,500 per plan for multiple years | DFVCP notice (2013); 29 CFR 2560.502c-2 |
| DFVCP: large plan (100 or more participants) | $10 per day | $2,000 per filing; $4,000 per plan for multiple years | DFVCP notice (2013); 29 CFR 2560.502c-2 |
| DFVCP: small plan of a 501(c)(3) organization | $10 per day | $750 per plan, regardless of the number of late filings | DFVCP notice (2013) |
A plan that qualifies for DFVCP and separately files any required Form 8955-SSA with the IRS also receives IRS penalty relief under Notice 2014-35. DOL amounts adjust annually for inflation; confirm the current-year figure before assuming exposure.
DFVCP basics: how to file late with a capped penalty
- Confirm eligibility. The program is open to administrators of ERISA Title I plans who have not yet received written notice from the DOL of a failure to file on time. Owner-only plans that file Form 5500-EZ use the IRS’s separate program instead.
- Prepare each missed year in full. Every delinquent Form 5500 needs its schedules and, for a large plan, the audit report. EFAST2 accepts prior-year forms; older years may use the current form with the actual plan-year dates.
- Check the DFVC box in Part I of Form 5500 and file electronically through EFAST2.
- Pay the penalty through the DOL’s online DFVCP calculator and payment system (or by mail): $10 per day late, capped per filing and per plan as shown above.
- File Form 8955-SSA with the IRS if the plan was required to file one, so IRS penalty relief applies.
Working back from the deadline: a calendar-year plan
| When | What happens | Who |
|---|---|---|
| January – February | Confirm large-plan status from the January 1 participant count; sign the engagement letter; agree the fieldwork calendar. | Sponsor, auditor |
| March | Deliver the document request list; request the ERISA Section 103(a)(3)(C) certification and SOC 1 reports from the recordkeeper and custodian. | Sponsor |
| April – June | Planning, walkthroughs, and fieldwork; sponsor answers open items within days, not weeks. | Auditor, sponsor |
| Early July | Draft financial statements and a substantially complete draft Form 5500 go to the auditor (the auditor must read the draft before dating the report). | Sponsor, preparer |
| July 31 | File Form 5500 with the audit report attached — or file Form 5558 on or before this date. | Plan administrator |
| August – September | Finish open items, obtain the signed opinion, attach it to the filing. | Auditor, sponsor |
| October 15 | Extended Form 5500 deadline. No further extension exists. | Plan administrator |
Capacity is the constraint, not the calendar. Plan year 2024 Form 5500 data contains 77,427 audited filings signed by 4,052 firms, and most plans are calendar-year filers — so the same firms face the same July 31 and October 15 dates for nearly every client at once. Firms fill spring fieldwork slots first; engagements that start after Labor Day pay for the compression.
Rankings derived from U.S. Department of Labor Form 5500 filings, plan year 2024. Read the full methodology.
401(k) audit deadline FAQs
Is the 401(k) audit due at the same time as Form 5500?
Yes. The independent accountant’s report is an attachment to Form 5500, not a separate filing, so it shares the Form 5500 due date: the last day of the seventh month after the plan year ends, or the Form 5558 extended date. A large-plan filing submitted without the required report is treated as incomplete.
Can I get a second extension for a 401(k) audit?
No. Form 5558 grants a single automatic extension of 2½ months. Beyond that date there is no further extension; the options are to file the complete return late under the Delinquent Filer Voluntary Compliance Program or to accept exposure to Department of Labor and IRS late-filing penalties.
What if July 31 or October 15 falls on a weekend?
The Form 5500 instructions allow filing on the next day that is not a Saturday, Sunday, or federal holiday. The extended deadline follows the same rule. Auditors, however, schedule around the nominal date, so treat the weekend rule as a cushion, not a plan.
When is the audit due for a fiscal-year or short plan year?
The same seventh-month rule applies: a plan year ending June 30 is due January 31 and can be extended to April 15. A short plan year of seven months or fewer is still filed on time, but the plan may defer the audit under 29 CFR 2520.104-50 and attach one audit covering both periods to the following year’s Form 5500.
What happens if I file Form 5500 without the audit report?
The Department of Labor treats a large-plan filing without an independent accountant’s report as deficient. EBSA typically sends a notice giving the plan administrator 45 days to submit a complete filing; if it is not corrected, the return is rejected and penalties can be assessed as if it had never been filed. Once the DOL has notified you in writing, DFVCP is no longer available.
Does DFVCP also remove IRS penalties?
Generally, yes. Under IRS Notice 2014-35, the IRS will not assess its late-filing penalties for Form 5500 on a Title I plan that satisfies the DFVCP requirements and separately files any required Form 8955-SSA with the IRS. The DOL penalty under DFVCP is capped at $2,000 per filing for a large plan and $4,000 per plan for multiple years.
This page summarizes ERISA, Department of Labor regulations, and Form 5500 instructions in plain language for research purposes; confirm specifics with your ERISA counsel or auditor.