Best 401(k) Audit Firms (2026): Ranked by Verified Engagement Volume
The 401(k) audit firms with the most verified engagements, ranked from every audited Form 5500 filing in plan year 2024 — with the client-size, footprint, and opinion data you need to tell which of them fits your plan.
Last updated · Source data: plan year 2024 Form 5500 filings
Which are the best 401(k) audit firms?
Baker Tilly US, LLP leads with 3,633 retirement plan audits in plan year 2024; CliftonLarsonAllen LLP (3,276) and Forvis Mazars, LLP (2,583) follow. The best fit depends on plan size and state, so the tables below also rank firms for small plans, large plans, specialists, and the largest states.
How this ranking works
- Primary criterion: verified engagement volume. Each firm is ranked by the number of retirement plan audits (401(k), 403(b), profit-sharing, ESOP, and defined benefit plans) it signed as independent qualified public accountant in plan year 2024 Form 5500 filings, grouped by firm EIN. Ties break alphabetically. The national top 100 ranks on all audited filings including welfare plans; that figure is the second column.
- Secondary signals, shown for every firm: states and territories with at least one client; share of unmodified (clean) opinions among the firm’s coded retirement plan opinions; average client size (mean beginning-of-year participants); and the number and share of the firm’s engagements that are small plans (under 200 participants) or large plans (5,000 or more participants). These do not change the order.
- Segment tables re-rank firms with at least 25 retirement engagements by small-plan count, large-plan count, and specialization (at least 99% of audited filings are retirement plans), and show the leading firm in each of the five largest state markets.
- Not considered: audit fees, staffing, AICPA Employee Benefit Plan Audit Quality Center membership, and peer review results — none appear in Form 5500. See what this ranking can’t tell you. No firm pays to be listed or ranked.
3,956 firms audited at least one retirement plan in plan year 2024. The 25 firms below audited 26,694 of the 72,776 audited retirement plans (36.7%).
The 25 best 401(k) audit firms by verified volume
| # | Firm | Retirement plans audited | All audited filings | States | Unmodified opinions | Avg. client (participants) | Plans under 200 | Plans 5,000+ |
|---|---|---|---|---|---|---|---|---|
| 1 | Baker Tilly US, LLP | 3,633 | 3,776 | 51 | 98.4% | 2,136 | 573 (15.8%) | 292 (8.0%) |
| 2 | CliftonLarsonAllen LLP | 3,276 | 3,451 | 51 | 96.1% | 1,502 | 684 (20.9%) | 180 (5.5%) |
| 3 | Forvis Mazars, LLP | 2,583 | 2,687 | 52 | 97.9% | 1,981 | 465 (18.0%) | 160 (6.2%) |
| 4 | CBIZ CPAS P.C. | 1,616 | 1,663 | 48 | 97.5% | 2,237 | 329 (20.4%) | 111 (6.9%) |
| 5 | BDO USA, P.C. | 1,237 | 1,288 | 45 | 93.9% | 3,242 | 157 (12.7%) | 151 (12.2%) |
| 6 | Plante & Moran, PLLC | 1,182 | 1,217 | 45 | 96.6% | 1,896 | 195 (16.5%) | 90 (7.6%) |
| 7 | Eide Bailly LLP | 1,144 | 1,204 | 42 | 97.9% | 1,441 | 260 (22.7%) | 49 (4.3%) |
| 8 | Caron & Bletzer, PLLC | 1,133 | 1,138 | 41 | 99.5% | 863 | 316 (27.9%) | 29 (2.6%) |
| 9 | RSM US LLP | 954 | 984 | 45 | 92.8% | 1,490 | 154 (16.1%) | 42 (4.4%) |
| 10 | Crowe LLP | 930 | 975 | 40 | 98.6% | 4,730 | 108 (11.6%) | 124 (13.3%) |
| 11 | Pension Assurance LLP | 918 | 918 | 42 | 96.5% | 756 | 312 (34.0%) | 17 (1.9%) |
| 12 | WithumSmith+Brown, PC | 870 | 1,023 | 39 | 98.5% | 5,491 | 170 (19.5%) | 86 (9.9%) |
| 13 | Grant Thornton LLP | 781 | 816 | 40 | 93.3% | 5,006 | 81 (10.4%) | 153 (19.6%) |
| 14 | Wipfli LLP | 764 | 785 | 42 | 98.6% | 1,071 | 185 (24.2%) | 31 (4.1%) |
| 15 | CohnReznick LLP | 703 | 728 | 35 | 97.2% | 1,862 | 130 (18.5%) | 53 (7.5%) |
| 16 | EisnerAmper LLP | 580 | 591 | 31 | 99.3% | 1,439 | 122 (21.0%) | 34 (5.9%) |
| 17 | PKF O'Connor Davies, LLP | 577 | 585 | 27 | 96.9% | 1,070 | 151 (26.2%) | 19 (3.3%) |
| 18 | Ernst & Young LLP | 519 | 629 | 42 | 95.6% | 21,834 | 34 (6.6%) | 218 (42.0%) |
| 19 | Sikich CPA LLC | 510 | 541 | 33 | 97.5% | 822 | 134 (26.3%) | 14 (2.7%) |
| 20 | Cherry Bekaert LLP | 493 | 508 | 28 | 98.8% | 1,255 | 116 (23.5%) | 20 (4.1%) |
| 21 | Citrin Cooperman & Company, LLP | 472 | 502 | 20 | 98.7% | 905 | 127 (26.9%) | 12 (2.5%) |
| 22 | Armanino LLP | 462 | 480 | 35 | 97.0% | 1,924 | 83 (18.0%) | 19 (4.1%) |
| 23 | UHY LLP | 459 | 472 | 31 | 98.5% | 1,245 | 129 (28.1%) | 13 (2.8%) |
| 24 | Deloitte & Touche LLP | 455 | 569 | 41 | 96.9% | 14,274 | 26 (5.7%) | 168 (36.9%) |
| 25 | Bonadio & Co., LLP | 443 | 482 | 22 | 97.3% | 1,194 | 88 (19.9%) | 16 (3.6%) |
Rankings derived from U.S. Department of Labor Form 5500 filings, plan year 2024. Read the full methodology.
The top 10 in detail
1. Baker Tilly US, LLP
Baker Tilly US, LLP audited 3,633 retirement plans in plan year 2024 (3,776 audited filings including welfare plans), with clients in 51 states and territories; California is its largest market (867 plans, 23.9% of its engagements). The average client has 2,136 participants, and its largest audited plan reports 197,749. Of its engagements, 573 (15.8%) are plans under 200 participants and 292 (8.0%) have 5,000 or more; unmodified opinions were issued on 98.4% of its retirement plan filings. Full profile · Alternatives
2. CliftonLarsonAllen LLP
CliftonLarsonAllen LLP audited 3,276 retirement plans in plan year 2024 (3,451 audited filings including welfare plans), with clients in 51 states and territories; Minnesota is its largest market (444 plans, 13.6% of its engagements). The average client has 1,502 participants, and its largest audited plan reports 249,207. Of its engagements, 684 (20.9%) are plans under 200 participants and 180 (5.5%) have 5,000 or more; unmodified opinions were issued on 96.1% of its retirement plan filings. Full profile · Alternatives
3. Forvis Mazars, LLP
Forvis Mazars, LLP audited 2,583 retirement plans in plan year 2024 (2,687 audited filings including welfare plans), with clients in 52 states and territories; North Carolina is its largest market (217 plans, 8.4% of its engagements). The average client has 1,981 participants, and its largest audited plan reports 286,355. Of its engagements, 465 (18.0%) are plans under 200 participants and 160 (6.2%) have 5,000 or more; unmodified opinions were issued on 97.9% of its retirement plan filings. Full profile · Alternatives
4. CBIZ CPAS P.C.
CBIZ CPAS P.C. audited 1,616 retirement plans in plan year 2024 (1,663 audited filings including welfare plans), with clients in 48 states and territories; New York is its largest market (203 plans, 12.6% of its engagements). The average client has 2,237 participants, and its largest audited plan reports 645,304. Of its engagements, 329 (20.4%) are plans under 200 participants and 111 (6.9%) have 5,000 or more; unmodified opinions were issued on 97.5% of its retirement plan filings. Full profile · Alternatives
5. BDO USA, P.C.
BDO USA, P.C. audited 1,237 retirement plans in plan year 2024 (1,288 audited filings including welfare plans), with clients in 45 states and territories; New York is its largest market (181 plans, 14.6% of its engagements). The average client has 3,242 participants, and its largest audited plan reports 141,948. Of its engagements, 157 (12.7%) are plans under 200 participants and 151 (12.2%) have 5,000 or more; unmodified opinions were issued on 93.9% of its retirement plan filings. Full profile · Alternatives
6. Plante & Moran, PLLC
Plante & Moran, PLLC audited 1,182 retirement plans in plan year 2024 (1,217 audited filings including welfare plans), with clients in 45 states and territories; Michigan is its largest market (406 plans, 34.3% of its engagements). The average client has 1,896 participants, and its largest audited plan reports 185,135. Of its engagements, 195 (16.5%) are plans under 200 participants and 90 (7.6%) have 5,000 or more; unmodified opinions were issued on 96.6% of its retirement plan filings. Full profile · Alternatives
7. Eide Bailly LLP
Eide Bailly LLP audited 1,144 retirement plans in plan year 2024 (1,204 audited filings including welfare plans), with clients in 42 states and territories; Minnesota is its largest market (125 plans, 10.9% of its engagements). The average client has 1,441 participants, and its largest audited plan reports 135,136. Of its engagements, 260 (22.7%) are plans under 200 participants and 49 (4.3%) have 5,000 or more; unmodified opinions were issued on 97.9% of its retirement plan filings. Full profile · Alternatives
8. Caron & Bletzer, PLLC
Caron & Bletzer, PLLC audited 1,133 retirement plans in plan year 2024 (1,138 audited filings including welfare plans), with clients in 41 states and territories; Massachusetts is its largest market (393 plans, 34.7% of its engagements). The average client has 863 participants, and its largest audited plan reports 21,906. Of its engagements, 316 (27.9%) are plans under 200 participants and 29 (2.6%) have 5,000 or more; unmodified opinions were issued on 99.5% of its retirement plan filings. Full profile · Alternatives
9. RSM US LLP
RSM US LLP audited 954 retirement plans in plan year 2024 (984 audited filings including welfare plans), with clients in 45 states and territories; Illinois is its largest market (151 plans, 15.8% of its engagements). The average client has 1,490 participants, and its largest audited plan reports 75,540. Of its engagements, 154 (16.1%) are plans under 200 participants and 42 (4.4%) have 5,000 or more; unmodified opinions were issued on 92.8% of its retirement plan filings. Full profile · Alternatives
10. Crowe LLP
Crowe LLP audited 930 retirement plans in plan year 2024 (975 audited filings including welfare plans), with clients in 40 states and territories; Illinois is its largest market (155 plans, 16.7% of its engagements). The average client has 4,730 participants, and its largest audited plan reports 346,164. Of its engagements, 108 (11.6%) are plans under 200 participants and 124 (13.3%) have 5,000 or more; unmodified opinions were issued on 98.6% of its retirement plan filings. Full profile · Alternatives
Best 401(k) audit firms by segment
Volume alone favors the largest national practices. The tables below re-rank firms with at least 25 retirement engagements by the part of the market that matches your plan: small plans, large plans, retirement-plan specialists, and the leading firm in each of the five largest states.
Best for small plans (under 200 participants)
| # | Firm | Plans under 200 | Share of firm's engagements | All retirement plans | Avg. client (participants) |
|---|---|---|---|---|---|
| 1 | CliftonLarsonAllen LLP | 684 | 20.9% | 3,276 | 1,502 |
| 2 | Baker Tilly US, LLP | 573 | 15.8% | 3,633 | 2,136 |
| 3 | Forvis Mazars, LLP | 465 | 18.0% | 2,583 | 1,981 |
| 4 | CBIZ CPAS P.C. | 329 | 20.4% | 1,616 | 2,237 |
| 5 | Caron & Bletzer, PLLC | 316 | 27.9% | 1,133 | 863 |
| 6 | Pension Assurance LLP | 312 | 34.0% | 918 | 756 |
| 7 | Eide Bailly LLP | 260 | 22.7% | 1,144 | 1,441 |
| 8 | Plante & Moran, PLLC | 195 | 16.5% | 1,182 | 1,896 |
| 9 | Wipfli LLP | 185 | 24.2% | 764 | 1,071 |
| 10 | Lee CPA Audit Group | 172 | 43.7% | 394 | 363 |
Best for large plans (5,000 or more participants)
| # | Firm | Plans 5,000+ | Share of firm's engagements | Avg. client (participants) | Largest client (participants) |
|---|---|---|---|---|---|
| 1 | Baker Tilly US, LLP | 292 | 8.0% | 2,136 | 197,749 |
| 2 | Ernst & Young LLP | 218 | 42.0% | 21,834 | 1,921,006 |
| 3 | CliftonLarsonAllen LLP | 180 | 5.5% | 1,502 | 249,207 |
| 4 | Deloitte & Touche LLP | 168 | 36.9% | 14,274 | 318,750 |
| 5 | Forvis Mazars, LLP | 160 | 6.2% | 1,981 | 286,355 |
| 6 | Grant Thornton LLP | 153 | 19.6% | 5,006 | 307,988 |
| 7 | BDO USA, P.C. | 151 | 12.2% | 3,242 | 141,948 |
| 8 | PricewaterhouseCoopers LLP | 137 | 39.0% | 13,426 | 303,498 |
| 9 | Crowe LLP | 124 | 13.3% | 4,730 | 346,164 |
| 10 | CBIZ CPAS P.C. | 111 | 6.9% | 2,237 | 645,304 |
Best regional specialists (at least 99% retirement plans)
| # | Firm | Retirement plans audited | Retirement share of filings | Largest state (share) | States |
|---|---|---|---|---|---|
| 1 | Caron & Bletzer, PLLC | 1,133 | 99.6% | MA (34.7%) | 41 |
| 2 | Pension Assurance LLP | 918 | 100.0% | CA (63.8%) | 42 |
| 3 | Smith & Howard, PC | 434 | 99.3% | GA (32.7%) | 34 |
| 4 | Doeren Mayhew Assurance | 418 | 99.8% | MI (37.3%) | 40 |
| 5 | Lee CPA Audit Group | 394 | 99.7% | CA (46.7%) | 36 |
| 6 | PriceKubecka, PLLC | 349 | 100.0% | TX (34.7%) | 36 |
| 7 | Holthouse Carlin & Van Trigt LLP | 325 | 99.7% | CA (86.2%) | 19 |
| 8 | Assurance Dimensions | 283 | 100.0% | FL (72.8%) | 26 |
| 9 | Clark Nuber P.S. | 245 | 99.2% | WA (86.5%) | 12 |
| 10 | Templeton & Company | 239 | 99.2% | FL (33.9%) | 38 |
Best in the five largest state markets
| State | Audited retirement plans | Leading firm | Plans (share of state) | Runner-up |
|---|---|---|---|---|
| California | 8,081 | Baker Tilly US, LLP | 867 (10.7%) | Pension Assurance LLP (586) |
| New York | 5,755 | Bonadio & Co., LLP | 369 (6.4%) | PKF O'Connor Davies, LLP (328) |
| Texas | 4,845 | Baker Tilly US, LLP | 308 (6.4%) | Weaver and Tidwell, LLP (273) |
| Pennsylvania | 3,672 | Baker Tilly US, LLP | 311 (8.5%) | Kreischer Miller (174) |
| Illinois | 3,540 | Sikich CPA LLC | 228 (6.4%) | CliftonLarsonAllen LLP (221) |
Rankings derived from U.S. Department of Labor Form 5500 filings, plan year 2024. Read the full methodology.
What this ranking can’t tell you
- Fees. Form 5500 does not report audit fees, so no fee data enters this ranking. The cost guide publishes editorial fee bands by plan size and a calculator, labeled as estimates.
- Quality beyond opinion type. An unmodified opinion says the plan’s financial statements were fairly presented; it says nothing about how thorough the audit was. Volume is the best public proxy — the Department of Labor’s audit quality study found deficiency rates of 76% among CPAs performing one or two plan audits a year versus 12% at the largest practices — but peer review results, AICPA Employee Benefit Plan Audit Quality Center membership, and DOL inspection findings are not in the data.
- Staffing and service. Who performs the fieldwork, experience with your recordkeeper and payroll systems, turnaround before the Form 5500 deadline, and whether the fee assumes an ERISA Section 103(a)(3)(C) election all come from the proposal, not the filing. The guide to switching auditors covers what to ask, and the audit checklist shows what a firm will request from you.
- Firm structure. Firms are grouped by the EIN on the filing, so a firm that files under several EINs after a merger or rebrand can appear split; see the methodology.
Best 401(k) audit firms: FAQs
Which firm audits the most 401(k) plans?
Baker Tilly US, LLP audited 3,633 retirement plan filings in plan year 2024, more than any other firm, followed by CliftonLarsonAllen LLP (3,276) and Forvis Mazars, LLP (2,583). Counts are Form 5500 filings on which the firm is named as independent qualified public accountant, grouped by the firm's EIN.
How were the best 401(k) audit firms ranked?
By the number of retirement plan audits (401(k), 403(b), profit-sharing, ESOP, and defined benefit plans) each firm signed as independent qualified public accountant in plan year 2024 Form 5500 filings, grouped by firm EIN, with ties broken alphabetically. Secondary signals — states served, opinion mix, average client size, and the number of small (under 200 participants) and large (5,000 or more) plans audited — are shown for each firm but do not change the order. No firm pays to be listed or ranked.
Do the Big Four audit 401(k) plans?
Yes, but at lower volume and for much larger plans than the market as a whole. Ernst & Young ranks #18 by retirement plan volume with 519 audits and an average client of 21,834 participants, and Deloitte & Touche ranks #24 with 455 audits (average 14,274 participants), against a market-wide median plan of 357 participants. Regional and national CPA firms audit the large majority of 401(k) plans.
Does a higher rank mean a better 401(k) audit?
No. Engagement volume measures experience, which the Department of Labor’s audit quality study found to be strongly associated with fewer audit deficiencies, but it does not measure fees, staffing, responsiveness, or fit with your recordkeeper and payroll systems, none of which appear in Form 5500. Use the ranking to build a shortlist, then compare proposals on those points.