A plan audit has a hard external deadline: the Form 5500 with the audit report attached. Missing it exposes the plan administrator to penalties, and the deadline is the same for every calendar-year plan, so every firm's plan audits land in the same weeks. This guide sets out the dates from the 2025 Form 5500 instructions, the two extension routes, and a working calendar. The audit scope questions are covered in the 401(k) audit requirements guide and the Form 5500 filing guide.
The base due date
All required forms, schedules, statements, and attachments must be filed by the last day of the 7th calendar month after the end of the plan year. For a calendar-year plan, that is July 31. If the due date falls on a Saturday, Sunday, or federal holiday, the filing is timely on the next day that is not one of those.
Two consequences:
- The audit report is part of the filing. The Form 5500 instructions state that the regulations that excuse certain information from the audit do not exempt the administrator from engaging an independent qualified public accountant or from attaching the accountant's report to the Form 5500. A return without the report is incomplete.
- Short plan years follow the same rule. A plan year of less than 12 months is due the last day of the 7th month after the short year ends, or the extended due date.
The return is filed electronically through the ERISA Filing Acceptance System (EFAST2) using approved software or IFILE.
Extension route 1: Form 5558
A plan can obtain a one-time extension of up to 2.5 months by filing IRS Form 5558, Application for Extension of Time To File Certain Employee Plan Returns, on or before the normal due date of the return, not counting any extensions. The plan keeps a copy of the completed extension request with its records. On the Form 5500, the filer checks the Part I, line D box for extension using Form 5558.
For a calendar-year plan the extended date is October 15. The IRS states that Form 5558 is the form for a one-time extension for Forms 5500, 5500-SF, 5500-EZ, and 8955-SSA. Since January 9, 2024, it no longer covers Form 5330.
The Form 5558 extension is one-time, and the automatic extension below cannot be extended further with a Form 5558.
Extension route 2: the automatic extension with the tax return
An automatic extension to the due date of the employer's federal income tax return applies when all three conditions are met:
- The plan year and the employer's tax year are the same.
- The employer has been granted an extension of time to file its income tax return to a date later than the normal Form 5500 due date.
- A copy of the extension application for the income tax return is kept with the filer's records.
The extension cannot be extended further by filing Form 5558, and it cannot run beyond a total of 9.5 months after the close of the plan year. On the Form 5500, the filer checks the Part I, line D box for extension using the automatic extension.
A tax-exempt organization that is not required to file an income tax return and that requests an extension for its Form 990 series return with Form 8868 receives the same automatic extension to the extended Form 990 due date, if the conditions are met, again capped at 9.5 months.
Choose the route from the sponsor's facts:
| Situation | Extension route |
|---|---|
| Calendar-year plan, employer on calendar-year tax year with extended return | Automatic, to the extended return date, capped at 9.5 months |
| Plan year differs from the employer's tax year | Form 5558 |
| Employer did not extend its return | Form 5558 |
| Tax-exempt sponsor with extended Form 990 | Automatic, capped at 9.5 months |
For a calendar-year plan with a calendar-year corporate sponsor, the extended return date and the Form 5558 date coincide at October 15.
What an extension does not cover
The instructions note that an extension of time to file the Form 5500 does not operate as an extension for a Form 5500 filed for a direct filing entity other than a DCG or GIA, for PBGC premiums or ERISA section 4010 reports, or for Form 8955-SSA. A direct filing entity other than a DCG or GIA files no later than 9.5 months after the end of the entity's year.
If the deadline passes
The instructions describe the Delinquent Filer Voluntary Compliance (DFVC) Program, under which plan administrators who are delinquent in filing the annual report pay reduced civil penalties for voluntarily complying. The filer checks the DFVC box in Part I, line D. The DOL provides an online calculator for the amounts. The administrative penalty ceiling in the 2025 instructions is up to $2,739 a day for failing to file a complete and accurate report.
Working calendar for a calendar-year plan
Dates below are for the plan year ending December 31 with a July 31 base due date and an October 15 extended date. Add the weekend rule where a date falls on a Saturday or Sunday; July 31, 2027 is a Saturday, so the base due date for the 2026 plan year moves to Monday, August 2, 2027.
| When | Action |
|---|---|
| Nov to Dec | Set filing status: participant count as of January 1, 80-120 election, waiver conditions. See the 80-120 rule guide. Send engagement letters and the client request list. |
| January | Collect plan year-end trust statements, payroll registers, and the census. Request the certification from the institution if a 103(a)(3)(C) audit is elected; it is due from the institution within 120 days after year end. |
| February to March | Planning memo, risk assessment, preliminary tie-out of the trust statement to the trial balance. Contribution timing tests on payroll data. See participant data and late deposits. |
| April | Participant data testing, allocation recalculation, benefit payment and loan samples. Resolve exceptions with the client. |
| May | Draft financial statements, notes, and supplemental schedules. Complete the schedule of delinquent participant contributions. |
| June | Review, report drafting, management representation letter, and draft Form 5500 procedures. |
| By July 15 | Decide on the extension. File Form 5558 on or before the base due date, or keep the tax-return extension on file. |
| July 31 or next business day | File the Form 5500 with the audit report, or hold the extension. |
| Aug to Oct 15 | Extended-season completion. The report is dated no earlier than when the auditor has sufficient appropriate evidence, including the draft Form 5500 procedures. File by October 15. |
The practical rule: do not plan the report date around October 15 as if it were the standard. It is the outer limit of a one-time extension, and a firm that treats it as the target has no slack for a client delay.
Dating the report
Under SAS 136 the auditor's report cannot be dated earlier than the date the auditor obtains sufficient appropriate evidence, which includes the completed financial statements and disclosures, management's assertion that it has taken responsibility for them, and performance of the draft Form 5500 procedures. The Form 5500 procedures sit on the critical path to the report date, so schedule them before the report draft, not after.
CORAA prepares the planning schedules, the tie-outs, and the supplemental schedule drafts from the client's records, so the calendar above starts from files that are ready to review. You make the extension decision and you sign the report.
Sources
- DOL EBSA, 2025 Instructions for Form 5500 (Section 2 When To File; Extension of Time to File; DFVC; Penalties): https://www.dol.gov/agencies/ebsa/employers-and-advisers/plan-administration-and-compliance/reporting-and-filing/form-5500
- IRS, About Form 5558: https://www.irs.gov/forms-pubs/about-form-5558
- RSM US, SAS 136 changes to the auditor's report (report dating): https://www.rsmus.com/insights/financial-reporting/sas-136-changes-to-the-auditors-report
- 29 CFR 2520.103-5, eCFR: https://www.ecfr.gov/current/title-29/section-2520.103-5
CORAA prepares ready-to-review audit files for US CPA firms from client books; you review and sign. See /us.
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