How Much Does a 401(k) Audit Cost in Michigan?

Fee ranges by plan size, and what the Michigan audit market looks like in plan year 2024 Form 5500 filings: how many plans are audited, by how many firms, at what plan size, and who does the most of it.

Last updated September 6, 2026 · Source data: plan year 2024 Form 5500 filings

How much does a 401(k) audit cost in Michigan?

A 401(k) audit in Michigan typically costs $8,000–$18,000 a year — the national range, since fees track plan size, not geography. Michigan’s median audited plan (344 participants) falls in the $10,000 – $18,000 band. In plan year 2024, 283 firms audited 2,487 plans sponsored in Michigan.

2,487Audited plans in MI

283Active audit firms

344Median plan size (participants)

3.4%Share of U.S. audited plans

Typical 401(k) audit fees for Michigan plans

Typical annual 401(k) audit fee ranges by plan size (editorial estimates)
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 participantsMI median plan: 344 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, and not specific to Michigan. The market figures below are from the dataset. A first-year audit adds roughly 10–25%; an ERISA Section 103(a)(3)(C) election removes roughly 15–40%. See the national cost guide for the full list of fee drivers.

The Michigan audit market: the numbers behind a quote

Michigan employee benefit plan audit market, plan year 2024
Measure	Michigan	United States
Audited retirement plans (sponsor address in Michigan)	2,487	72,776
Audit firms with at least one engagement	283	3,956
Audited plans per active firm	8.8	18.4
Median audited plan size (participants)	344	357
Share of plans audited by the ten most active firms	51%	24%
Most active firm’s share of plans	16%	5%

National concentration is the share of all retirement plan engagements held by the ten largest firms nationally; the Michigan figure is the share of MI-sponsored plans audited by the ten most active firms in the state. State reflects the plan sponsor’s address, not the audit firm’s offices.

Michigan’s median is close to the national median of 357 participants, so the national fee framework applies without adjustment. The market is concentrated: the ten most active firms audited 51% of Michigan’s plans, so expect established regional and national practices to compete for your engagement — and to price against each other.

Rankings derived from U.S. Department of Labor Form 5500 filings, plan year 2024. Read the full methodology.

Most active 401(k) audit firms in Michigan

Firms ranked by audited retirement plan filings sponsored in Michigan, plan year 2024
#	Firm	MI plans audited	Share of state
1	Plante & Moran, PLLC	406	16.3%
2	Doeren Mayhew Assurance	156	6.3%
3	Rehmann Robson LLC	136	5.5%
4	UHY LLP	102	4.1%
5	Hungerford	97	3.9%
6	Baker Tilly US, LLP	93	3.7%
7	Yeo & Yeo, P.C.	91	3.7%
8	BDO USA, P.C.	69	2.8%
9	Maner Costerisan	62	2.5%
10	MRPR Group, PC	51	2.1%

Top 10 firms shown. Counts are retirement plan filings (401(k), 403(b), profit-sharing, and pension) whose sponsor address is in Michigan. Volume measures experience, not quality or price.

Rankings derived from U.S. Department of Labor Form 5500 filings, plan year 2024. Read the full methodology.

The full ranked directory, with market totals, is at 401(k) audit firms in Michigan. Each firm profile shows engagement counts, states served, opinion mix, and the firm’s largest audited plans.

How to get a fair 401(k) audit quote in Michigan

Quote on the same scope. Tell every candidate whether the plan will elect an ERISA Section 103(a)(3)(C) audit, how many payroll systems it runs, and whether it files Form 11-K. Otherwise the low bid is usually the narrow one.
Engage before spring. Nearly every Michigan plan is due July 31 or October 15; firms fill fieldwork calendars first-come, and engagements that start after Labor Day pay for the compression. See the deadline guide.
Shortlist by volume. Ask three to five firms from the table above, or from the state directory, and check each profile for client sizes comparable to yours. A Michigan office is optional — audits are performed under national standards from recordkeeper and payroll data — but demonstrated volume is not.
Deliver clean records. Reconciled census, dated remittances, SOC 1 reports, and the certification in hand before fieldwork are the cheapest fee reduction available. The document checklist lists everything the auditor will request.

Michigan 401(k) audit cost FAQs

Do 401(k) audits cost more in Michigan?

No systematic premium applies. Audit fees are driven by participant count, plan complexity, and record quality rather than the sponsor’s location, and most engagements are performed remotely. Michigan’s median audited plan had 344 participants in plan year 2024, versus 357 nationally, which places a typical Michigan plan in the $10,000 – $18,000 editorial fee band.

How many firms audit 401(k) plans in Michigan?

283 audit firms signed at least one audit of a retirement plan sponsored in Michigan in plan year 2024, covering 2,487 audited plans (3.4% of the U.S. total). The ten most active firms accounted for 51% of those plans; the rest were spread across 273 other firms.

Which firm audits the most 401(k) plans in Michigan?

Plante & Moran, PLLC audited 406 Michigan retirement plans in plan year 2024, the most of any firm and 16% of the state’s audited plans. Doeren Mayhew Assurance (156) and Rehmann Robson LLC (136) ranked second and third. Engagement volume signals experience, not quality; each firm profile shows opinion mix and client sizes.

401(k) audit cost in other states

Same fee framework, different market. Each page carries the state’s audited plan count, active firms, median plan size, and most active auditors from plan year 2024 filings.