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

Fee ranges by plan size, and what the South Dakota 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 South Dakota?

A 401(k) audit in South Dakota typically costs $8,000–$18,000 a year — the national range, since fees track plan size, not geography. South Dakota’s median audited plan (324 participants) falls in the $10,000 – $18,000 band. In plan year 2024, 47 firms audited 221 plans sponsored in South Dakota.

221Audited plans in SD

47Active audit firms

324Median plan size (participants)

0.3%Share of U.S. audited plans

Typical 401(k) audit fees for South Dakota 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 participantsSD median plan: 324 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 South Dakota. 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 South Dakota audit market: the numbers behind a quote

South Dakota employee benefit plan audit market, plan year 2024
Measure	South Dakota	United States
Audited retirement plans (sponsor address in South Dakota)	221	72,776
Audit firms with at least one engagement	47	3,956
Audited plans per active firm	4.7	18.4
Median audited plan size (participants)	324	357
Share of plans audited by the ten most active firms	81%	24%
Most active firm’s share of plans	39%	5%

National concentration is the share of all retirement plan engagements held by the ten largest firms nationally; the South Dakota figure is the share of SD-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.

South Dakota’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 81% of South Dakota’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 South Dakota

Firms ranked by audited retirement plan filings sponsored in South Dakota, plan year 2024
#	Firm	SD plans audited	Share of state
1	Eide Bailly LLP	86	38.9%
2	Ketel Thorstenson, LLP	30	13.6%
3	Elo Prof LLC	22	10.0%
4	RSM US LLP	9	4.1%
5	CliftonLarsonAllen LLP	7	3.2%
6	Forvis Mazars, LLP	6	2.7%
7	Gardiner + Company	5	2.3%
8	Brady, Martz & Associates, P.C.	5	2.3%
9	Henjes, Conner & Williams PC	5	2.3%
10	Deloitte & Touche LLP	3	1.4%

Top 10 firms shown. Counts are retirement plan filings (401(k), 403(b), profit-sharing, and pension) whose sponsor address is in South Dakota. 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 South Dakota. 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 South Dakota

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 South Dakota 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 South Dakota 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.

South Dakota 401(k) audit cost FAQs

Do 401(k) audits cost more in South Dakota?

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. South Dakota’s median audited plan had 324 participants in plan year 2024, versus 357 nationally, which places a typical South Dakota plan in the $10,000 – $18,000 editorial fee band.

How many firms audit 401(k) plans in South Dakota?

47 audit firms signed at least one audit of a retirement plan sponsored in South Dakota in plan year 2024, covering 221 audited plans (0.3% of the U.S. total). The ten most active firms accounted for 81% of those plans; the rest were spread across 37 other firms.

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

Eide Bailly LLP audited 86 South Dakota retirement plans in plan year 2024, the most of any firm and 39% of the state’s audited plans. Ketel Thorstenson, LLP (30) and Elo Prof LLC (22) 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.