Limited Scope 103(a)(3)(C) Plan Audits Explained

If your retirement plan has reached the audit threshold, you may hear that you “qualify for a limited scope audit.” That can sound like good news—and often it is—but only if you understand what “limited” really means under ERISA and how it affects your Form 5500 filing. Below is a practical guide to limited scope 103(a)(3)(C) plan audits: what they are, what they do (and don’t) cover, and the steps plan sponsors can take to avoid surprises.

What is a limited scope 103(a)(3)(C) plan audit?

A limited scope audit is a type of employee benefit plan audit allowed under ERISA Section 103(a)(3)(C). In plain English, it lets the plan auditor reduce (or “limit”) audit procedures over certain investment information when that information is certified by a qualifying financial institution.

Most commonly, this comes up in a 401(k) plan audit when the plan’s investments are held at a bank, trust company, or insurance company that can provide a certification covering investment information.

Even though the audit is “limited,” it is still a real audit. The auditor still issues an audit report that is attached to the plan’s annual filing. If you’re new to plan filings, see our guide to what a Form 5500 is and how it fits into annual compliance.

Who qualifies—and what “certification” must include

Qualification generally depends on whether a permitted institution can certify the plan’s investment information. The certification typically covers the completeness and accuracy of investment data, such as:

• Investment holdings at year-end

• Investment transactions during the year

• Investment income

Not every service provider can issue a valid certification. In practice, plans often qualify when investments are held by a bank, insurance company, or similar regulated institution that meets ERISA’s requirements.

Important: A limited scope audit does not mean the plan sponsor has less responsibility. Plan fiduciaries still must ensure the plan’s records are accurate, contributions are handled properly, and the Form 5500 is complete and timely.

What a limited scope audit does NOT cover (and what auditors still test)

The “limited” part is primarily about investment information covered by the certification. For those certified investment amounts, the auditor generally does not perform the same level of detailed testing as in a full scope audit.

However, auditors still perform significant work in other areas. In a limited scope 103(a)(3)(C) audit, auditors commonly test:

• Participant data (eligibility, deferrals, employer match, compensation definitions)

• Contributions and remittances (including timeliness of employee deferrals)

• Loans and distributions (approvals, calculations, and compliance with plan terms)

• Plan expenses (reasonableness and proper allocation)

• Compliance with plan provisions (operating the plan the way the document says)

• Financial statement presentation and required supplemental schedules for the Form 5500

If you’re still determining whether you need an audit at all, start with What Is a 401(k) Audit and When Do I Need One?.

Pros and cons for plan sponsors

Limited scope audits can be beneficial, but they’re not “automatic” and not always simpler than expected.

Potential benefits include:

• Reduced audit testing over certified investments

• Potentially lower audit fees compared to a full scope audit (depending on plan complexity)

• Faster fieldwork in some cases, because investment confirmations/testing may be reduced

Potential drawbacks include:

• More scrutiny on non-investment areas (payroll, eligibility, remittances) where many issues occur

• Certification limitations: if the certification is incomplete or not from a qualifying institution, the auditor may need to expand procedures

• Misunderstandings about responsibility: the plan sponsor still owns the accuracy of records and filings

How to prepare for a smoother limited scope audit

Preparation is the difference between a smooth audit and a painful one. A limited scope audit still requires strong payroll and plan administration processes.

Here’s a practical checklist to get ahead of common requests:

1. Request the certification early from the institution holding plan assets and confirm it covers the correct plan year.

2. Reconcile payroll to contributions (employee deferrals and employer match/profit sharing) and document any corrections.

3. Review eligibility and entry dates for a sample of employees to confirm timely enrollment and correct deferral start dates.

4. Check loan and distribution files for approvals, calculations, and consistent withholding/reporting.

5. Organize plan documents (plan document, adoption agreement, amendments, SPD) so the auditor can verify plan provisions.

For a deeper document list, see What Is Needed for a 401(k) Audit and Where Do I Find It?.

Common mistakes that lead to delays (or Form 5500 problems)

Many audit delays happen because the plan sponsor assumes the investment certification is the only requirement. In reality, Form 5500 schedules, payroll support, and participant data drive a large portion of the work.

Watch out for these common issues:

• Late or missing certification (or certification not meeting ERISA requirements)

• Unreconciled payroll reports vs. contributions deposited to the trust

• Late remittance of employee deferrals without documentation and correction steps

• Inconsistent census data (compensation, hire dates, termination dates)

• Last-minute audit start that pushes the Form 5500 close to (or past) the deadline

Late filings can be expensive. See The High Cost of Non-Compliance: Penalties for Late or Rejected Form 5500 Audits for a plain-language overview of what’s at stake.

How to choose the right auditor (and when to get extra help)

Employee benefit plan audits are specialized. Working with an experienced firm can reduce rework and help you avoid filing issues.

If you’re evaluating providers, start with our directory of experienced 401(k) auditors (or browse all employee benefit plan auditors if you sponsor multiple plan types). If your organization has other plans, you may also need specialized support such as 403(b) auditors, defined benefit plan auditors, ESOP auditors, or health & welfare plan auditors.

It can also help to coordinate with a knowledgeable advisor and legal counsel, especially if you’ve had operational issues or corrections:

• How to Hire a Retirement Plan Advisor and our directory of 401(k) financial advisors

• ERISA attorneys for plan interpretation, corrections, and fiduciary questions

And while it’s separate from the audit itself, many plans also need an ERISA bond. If you’re unsure, read What Is An ERISA Bond And How To Buy One? or compare ERISA bond providers.

Authoritative guidance (official sources)

For official background and compliance expectations, these government resources are helpful:

• U.S. Department of Labor (EBSA) audit quality resources

• DOL/EBSA Form 5500 reporting and filing information

Conclusion: limited scope doesn’t mean low effort

A limited scope 103(a)(3)(C) plan audit can streamline testing over certified investments, but it does not eliminate the need for strong plan operations, clean payroll records, and timely Form 5500 preparation. If your plan is approaching an audit, start early, secure the certification, and make sure your internal team and service providers are aligned.

If you’re ready to compare firms, explore our network of 401(k) auditors and build an audit process that supports an accurate, on-time Form 5500 filing.