What a 401(k) plan auditor does
A plan auditor audits the plan’s financial statements, which are attached to the plan’s Form 5500 when the plan files as a large plan. The audit tests contributions and their timing, distributions, participant loans, investments and participant data.
The auditor works with your recordkeeper and third-party administrator and relies in part on their SOC 1 reports. In an ERISA Section 103(a)(3)(C) audit, certified investment information from a qualified bank or insurer is not audited again, but the rest of the work still happens.
See our employee benefit plan audit, 403(b) plan audit and defined benefit plan audit pages.
How to verify a 401(k) plan auditor’s license
- License. Search the firm and engagement partner on NASBA CPAverify or through NASBA’s state board directory.
- Peer review. Look up the firm’s latest report in the AICPA Peer Review public file. Ask whether the review included employee benefit plan engagements.
- Plan audit track record. Search EFAST2 for Form 5500 filings, where large plan filings include the auditor’s report.
- DOL guidance. Read the EBSA publication Selecting an Auditor for Your Employee Benefit Plan (September 2018). It says the auditor must hold a state license or certificate, be independent, and have training and experience in plan audits, and it suggests asking for peer review results.
Questions to ask a 401(k) plan auditor before hiring
- How many plan audits do you complete each year, and how many are plans like ours (401(k), 403(b), defined benefit)?
- Did your latest peer review include employee benefit plan audits? May we see it?
- How do you coordinate with our recordkeeper and TPA, and use their SOC 1 reports?
- Should we elect a 103(a)(3)(C) audit, and what does that change?
- What is your timeline relative to our Form 5500 due date and extension?
- How do you communicate findings such as late deposits of employee deferrals?
Free checklist
Plan Auditor Selection Checklist and First-Year PBC List
Red flags
- The firm does few or no plan audits and says “an audit is an audit.”
- No peer review report, or a review that did not cover plan audits.
- The CPA cannot explain the participant count rules or a 103(a)(3)(C) audit.
- Fieldwork is planned to start after the extended Form 5500 deadline.
- Your recordkeeper or TPA offers to “handle the audit” themselves.
Why clients choose Your Virtual CPA
- A licensed CPA firm auditing employee benefit plans nationwide, virtually.
- 401(k) and other benefit plan audits, 403(b) plan audits and SOC 1 reports for service providers.
- Free tools: the 401(k) audit requirement checker.
- Transparent fees quoted upfront, in writing, and a free initial consultation.
How it works with us
Best for: plan sponsors whose 401(k), 403(b) or defined benefit plan needs its first audit or a new auditor.
- Free initial consultation. Tell us the plan type, participant count, service providers and filing deadline.
- Fees quoted upfront, in writing. An engagement letter before work starts.
- Planning. We coordinate with your recordkeeper and TPA and send one document list.
- Testing. Contributions, distributions, loans and participant data, done virtually.
- Report. Audited financial statements ready to attach to Form 5500.
Your company’s CPA vs benefit plan audit specialist vs TPA or recordkeeper
| Company’s regular CPA | Plan audit specialist CPA firm | TPA or recordkeeper | |
|---|---|---|---|
| Audits the plan | Only if experienced and independent | Yes | No |
| Knows ERISA and Form 5500 audit rules | Varies | Yes | Knows filing, not auditing |
| Uses service provider SOC 1 reports | Varies | Yes | Provides them |
| Prepares Form 5500 | Sometimes | Sometimes | Often |
| Runs compliance testing | No | Tests the results | Yes |
| Holds participant records | No | No | Yes |
Expert CPAs. Personal attention.
Need a plan auditor before your Form 5500 deadline? Bring your plan details to a free initial consultation and talk to a CPA.
Frequently asked questions
Generally when the plan files Form 5500 as a large plan, which usually means 100 or more participants at the start of the plan year. For defined contribution plans, the count now includes only participants with account balances. The 80–120 participant rule can let a plan keep filing as a small plan. See our 401(k) audit requirements guide.
No. The audit must be performed by an independent qualified public accountant. Your recordkeeper and TPA provide the data and reports the auditor tests, so they cannot audit their own work.
Only if the firm is licensed, independent of the plan, and experienced in plan audits. The DOL’s guide on selecting a plan auditor says to weigh the auditor’s training and experience with benefit plans, not just the lowest fee, and to ask for peer review results.
Ask how many plan audits the firm completes each year and of what type. You can also search public Form 5500 filings on EFAST2, where large plan filings include the auditor’s report, to see plans the firm has audited.
It is an audit where certified investment information from a qualified bank or insurance carrier is not audited again. The auditor still tests contributions, distributions, loans and participant data. The plan administrator must decide whether to elect it.
Yes. Your Virtual CPA is a licensed CPA firm that audits employee benefit plans nationwide. Plan audits are largely document-based and work well virtually with your recordkeeper and TPA.
It depends on plan size, type, the number of service providers and whether the audit is a 103(a)(3)(C) audit. We quote fees upfront, in writing, after a free initial consultation.
Sources
- U.S. DOL EBSA: Selecting an Auditor for Your Employee Benefit Plan (September 2018, PDF)
- U.S. DOL EBSA: Form 5500 series
- U.S. DOL: EFAST2 Form 5500 search
- NASBA CPAverify
- AICPA Peer Review public file search
General information as of October 20, 2026. Tax rules change; talk to a CPA about your situation.