How Much Does a 401(k) Audit Cost?
Last updated · Source data: plan year 2024 Form 5500 filings
How much does a 401(k) audit cost?
Most single-employer 401(k) plan audits cost between $8,000 and $18,000 per year. A first-year audit of a plan near the 100-participant threshold typically runs $9,000–$14,000. Larger plans, employer stock, multiple payroll systems, or messy records push fees above $25,000.
Typical audit fees by plan size
| Plan size | Typical fee range | What drives the range |
|---|---|---|
| 100–249 participants | $8,000 – $14,000 | Most first-time audits land here; single payroll and one recordkeeper keep scope tight. |
| 250–499 participants | $10,000 – $18,000 | More participant-level testing; still typically one fieldwork cycle. |
| 500–999 participants | $13,000 – $25,000 | Larger samples; often multiple payrolls or acquisitions in the mix. |
| 1,000–4,999 participants | $18,000 – $40,000 | Complexity-driven: mergers, employer stock, non-standard assets push the top of the range. |
| 5,000+ participants | $30,000+ | Multi-entity sponsors, 11-K filers, and hard-to-value assets; fees are bespoke. |
Honest labeling: audit fees are not reported in a standardized, reliable field on Form 5500, so these ranges are editorial estimates informed by published fee surveys and engagement quotes — not outputs of our filing dataset. The benchmarks below are from the dataset.
Want a figure for your plan? Estimate your fee range with the calculator further down this page.
What makes a 401(k) audit more or less expensive?
| Factor | Effect on fee |
|---|---|
| Audit scope election | An ERISA Section 103(a)(3)(C) audit (investments certified by a qualified institution) typically runs 15–40% less than a full-scope audit. |
| First year vs. recurring | Year one adds opening-balance and setup work; expect a premium of roughly 10–25%, then modest annual increases. |
| Payroll and recordkeeping | Each additional payroll system, recordkeeper conversion, or mid-year provider change adds testing hours. |
| Plan design complexity | Employer securities, self-directed brokerage, non-participant-directed or hard-to-value assets, and DB components raise scope. |
| Condition of records | Clean census data, timely contribution remittances, and reconciled trust reports are the cheapest fee reduction available. |
| Timing | Engaging in spring for an October 15 extended deadline invites rush premiums; auditors discount predictable, early fieldwork. |
Benchmarks from 77,427 audited filings
Context for your quote, from plan year 2024 Form 5500 data. If your plan has 250 participants, you are shopping in the market’s crowded middle; if it has 5,000, only a subset of firms regularly audits at that scale.
| Plan size (participants, beginning of year) | Audited plans | Share |
|---|---|---|
| Under 100 participants | 367 | 0.5% |
| 100–249 | 24,961 | 34.3% |
| 250–499 | 19,494 | 26.8% |
| 500–999 | 11,914 | 16.4% |
| 1,000–4,999 | 11,935 | 16.4% |
| 5,000 or more | 4,105 | 5.6% |
Median audited plan: 357 participants. Plans under 100 participants appear mainly through the 80–120 rule and plans electing large-plan filing status.
| Measure | Value |
|---|---|
| Retirement plan audits held by the 10 largest firms | 17,688 (24.3%) |
| Retirement plan audits held by the 100 largest firms | 42,182 (58.0%) |
| Firms with at least one retirement plan engagement | 3,956 |
| Firms auditing exactly one plan | 1,552 |
| Median engagements per firm | 2 |
Pricing implication: the market has a competitive, specialized top tier and a very long tail of occasional auditors. Specialists are often cheaper per hour of assurance because the work is templated; occasional auditors may quote low but carry the deficiency risk documented by the DOL.
Rankings derived from U.S. Department of Labor Form 5500 filings, plan year 2024. Read the full methodology.
401(k) audit cost FAQs
Who pays for a 401(k) audit — the company or the plan?
Either. The audit supports the plan’s Form 5500 filing and is generally treated as a plan administrative expense, so it may be paid from plan assets if the plan document permits. In practice most sponsors pay it as a corporate expense to avoid reducing participant balances.
Is a cheaper audit riskier?
It can be. The U.S. Department of Labor’s audit quality study found a 76% deficiency rate among CPAs performing one or two plan audits per year, versus 12% at the largest practices. A deficient audit can lead the DOL to reject the Form 5500, exposing the sponsor to penalties. Weigh engagement volume — shown throughout this directory — alongside fee.
What is a Section 103(a)(3)(C) audit, and does it save money?
It is an election, formerly called a limited-scope audit, available when a bank, trust company, or insurance carrier certifies the plan’s investment information. The auditor then does not audit the certified investment figures, which reduces hours and cost — typically 15–40% versus full scope. Participant data, contributions, and distributions are still tested.
How long does a 401(k) audit take?
Plan on six to twelve weeks from kickoff to signed opinion for a typical plan, including sponsor time gathering payroll and census support. Audits begun after Labor Day for an October 15 extended Form 5500 deadline are feasible but compressed; spring engagement is cheaper and calmer.
Why did my audit fee go up this year?
Common causes: participant growth pushing larger samples, a recordkeeper or payroll conversion, an acquisition adding a merged plan, a new auditor re-establishing opening balances, or firm-wide rate increases — plan audit fees have risen roughly 5–10% annually in recent years amid staffing shortages.
401(k) audit cost by state
State pages combine the same fee guidance with local market data: how many plans were audited in the state, how many firms serve it, and which firms sign the most filings there.
- California
- New York
- Texas
- Pennsylvania
- Illinois
- Ohio
- Florida
- Massachusetts
- Michigan
- New Jersey
- Virginia
- Wisconsin
- Georgia
- Minnesota
- North Carolina
- Washington
- Maryland
- Indiana
- Missouri
- Tennessee
- Colorado
- Connecticut
- Arizona
- Oregon
- Kentucky
- Iowa
- Alabama
- Kansas
- Utah
- Louisiana
- Washington, D.C.
- South Carolina
- Oklahoma
- Nebraska
- New Hampshire
- Arkansas
- Nevada
- Maine
- Puerto Rico
- Idaho
- Mississippi
- Hawaii
- North Dakota
- Rhode Island
- West Virginia
- New Mexico
- Delaware
- South Dakota
- Montana
- Vermont
- Alaska
- Wyoming
- Guam
- U.S. Virgin Islands
- Northern Mariana Islands
Next steps
What will my 401(k) audit cost? Estimate a fee range
Enter your plan’s facts for an estimated annual fee range built from the editorial fee bands above. It is a planning estimate, not a quote, and not Form 5500 data — audit fees are not reported on the form.
Estimated annual audit fee (editorial estimate)
$8,000 – $14,000
| Factor | Your plan | Effect on fee |
|---|---|---|
| Plan size | 150 participants with balances | Base band 100–249 participants: $8,000 – $14,000 |
| First-year audit | No | No adjustment |
| Audit scope | ERISA Section 103(a)(3)(C) | No adjustment |
| Self-directed brokerage windows | No | No adjustment |
| Prior-year findings | No | No adjustment |
| Investment menu | 20 options | No adjustment |
| Plan assets | $15,000,000 | No adjustment |
- Adjustments compound. Employer stock, multiple payroll systems, mid-year recordkeeper changes, and messy records can push a real quote above this range.
Estimates start from the editorial fee bands in the table above and apply the percentage effects from the fee-drivers table. They are not derived from Form 5500 filings and are not a quote; get proposals from two or three firms with audit volume in your state.