The 401(k) Audit Market in 2026: Who Audits America’s Retirement Plans

Key findings

1. 77,427 audited filings, 4,052 firms. Plan year 2024 produced 77,427 Form 5500 filings naming an independent auditor on Schedule H. 72,776 (94.0%) are retirement plans (401(k), 403(b), profit-sharing, ESOP, and defined benefit); the rest are large welfare plans. 4,052 EIN-identified firms signed at least one audit; 3,956 signed at least one retirement-plan audit.
2. Baker Tilly, CliftonLarsonAllen, and Forvis Mazars lead. Baker Tilly US, LLP signed 3,776 audited filings (4.9% of the market), CliftonLarsonAllen 3,451 (4.5%), and Forvis Mazars 2,687 (3.5%). Each serves plan sponsors in 51 or 52 of the 55 U.S. jurisdictions in the data.
3. Ten firms hold 24.3% of retirement-plan engagements; 100 hold 58.0%. The top 500 firms hold 82.0%. Yet no firm exceeds a 5.0% share, and the Herfindahl-Hirschman Index is roughly 97, far below the 1,000 mark under which federal merger guidelines treat a market as unconcentrated.
4. Half of all firms audit one or two plans; together they hold 3.4% of the work. The median firm audited two plans. 1,552 firms (38.3%) audited exactly one, and 2,025 (50.0%) audited one or two, accounting for 2,498 of 72,722 engagements. At the other end, 437 firms with 25 or more engagements (10.8% of firms) performed 80.0% of retirement-plan audits, and 106 firms with 100 or more performed 58.9%.
5. The Big Four audit fewer plans than Baker Tilly alone, but far larger ones. Ernst & Young (629 filings), Deloitte & Touche (569), PricewaterhouseCoopers (536), and KPMG (334) signed 2,068 audited filings under their primary EINs, or 2,166 (2.8%) across all 43 EIN and name variants, against Baker Tilly’s 3,776. Their clients are an order of magnitude larger than the market: the average retirement plan audited by EY has 21,834 participants and by KPMG 20,917, versus a market-wide median of 357. The largest audited plan in the data, Walmart Inc.’s, reports 1,921,006 participants and is audited by EY.
6. Retirement-plan specialists outrank every Big Four firm. Caron & Bletzer, PLLC (1,138 filings, 99.6% retirement plans) ranks #8 and Pension Assurance LLP (918, 100% retirement plans) ranks #12; Ernst & Young, the largest Big Four EBP practice by count, ranks #16. 28 of the top 100 firms derive at least 99% of their audited filings from retirement plans.
7. Nearly two-thirds of firms work in a single state. 2,572 firms (63.5%) audited plans sponsored in only one state. 179 firms reach ten or more jurisdictions, 16 reach 40 or more, and three (Forvis Mazars, Baker Tilly, CliftonLarsonAllen) reach 50 or more.
8. California is 11.1% of the market. Plans sponsored in California account for 8,081 audited retirement filings, followed by New York (5,755), Texas (4,845), Pennsylvania (3,672), and Illinois (3,540). The ten largest states hold 54.3% of audited retirement plans; 23 jurisdictions have at least 1,000.
9. State leadership is split between national and regional firms. Baker Tilly and Eide Bailly each lead seven jurisdictions (Baker Tilly: CA, NM, OR, PA, TX, WA, WV; Eide Bailly: ID, MT, ND, NV, OK, SD, WY); CliftonLarsonAllen leads five and Forvis Mazars four. A national top-10 firm leads 30 of 55 jurisdictions, but 21 are led by a firm outside the national top 25, including Ohio (Clark, Schaefer, Hackett & Co., 258 plans), Tennessee (LBMC, 216), Florida (Assurance Dimensions, 206), and Nebraska (Lutz & Company, 121). Across the 50 states and D.C., the median leader holds 13.7% of its state’s audits, from 38.9% in South Dakota and 37.0% in North Dakota (both Eide Bailly) down to 6.4% in Texas, New York, and Illinois.
10. The typical audited plan is small. The median audited retirement plan has 357 participants; 34.3% have 100 to 249, 61.6% have fewer than 500, and 78.0% have fewer than 1,000. Only 5.6% (4,105 plans) have 5,000 or more. 367 plans with fewer than 100 participants were audited anyway, typically because of non-qualifying assets, short plan years, or the pre-2023 participant-counting method.
11. 96.9% of audits carried an unmodified opinion. Of 77,427 audited filings, 75,047 were unmodified, 247 qualified (0.3%), 2,023 disclaimers (2.6%), 2 adverse, and 108 reported no opinion type. Disclaimers are coded on 6.4% of engagements at firms with one to four plans versus 2.4% at firms with 100 or more. Because the disclaimer category historically captured limited-scope audits before SAS 136 replaced that report format, the gap is best read as a difference in reporting convention, not audit outcome.

Table 1. The ten largest employee benefit plan audit practices, plan year 2024

League-table basis: all audited Form 5500 filings signed under the firm’s EIN, including large welfare plans. Together the ten signed 18,431 filings, 23.8% of 77,427. Full top 100: national rankings.

Table 2. Firms by audit volume, plan year 2024

Retirement-plan filings attributed to EIN-identified firms. The 19 firms with 500 or more engagements audit more plans (23,910) than the 3,067 firms with one to nine engagements combined (7,767).

Table 3. The ten largest state markets and their leading firms, plan year 2024

State is the plan sponsor’s address on Form 5500, not the auditor’s office. “Active firms” have at least one audited retirement plan sponsored in the state. Shares are of the 72,690 retirement filings with a U.S. sponsor state. State directories: audit firms by state.

Table 4. Audited retirement plans by participant count, plan year 2024

Median: 357 participants. Highest state medians (50 states and D.C.): Tennessee (421), Georgia (414), New Jersey (410). Lowest among states with 200 or more audited plans: Vermont (286), North Dakota (293), New Mexico (297).

Cite this report

• Best 401(k) audit firms
• National top 100
• Audit firms by state
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