Olsen Thielen & Co., LTD
Employee benefit plan audit practice profile, built from plan year 2024 Form 5500 filings.
Last updated · Source data: plan year 2024 Form 5500 filings
How many 401(k) plans does Olsen Thielen & Co., LTD audit?
Olsen Thielen & Co., LTD was the independent auditor for 88 retirement plan filings (91 audited filings including welfare plans) in plan year 2024, with clients in 13 states and territories — the #130 practice nationally by volume.
Practice at a glance
| Measure | Value |
|---|---|
| Firm EIN (as filed) | 41-1360831 |
| Retirement plan audits (401(k), 403(b), pension) | 88 |
| All audited filings (incl. welfare plans) | 91 |
| States and territories with clients | 13 |
| National rank by retirement plan volume | #130 of 3,956 |
| National rank, all audited filings (league-table basis) | #132 of 4,052 |
| Average client size (participants) | 1,370 |
| Largest client (participants) | 35,291 |
Rankings derived from U.S. Department of Labor Form 5500 filings, plan year 2024. Read the full methodology.
Where does Olsen Thielen & Co., LTD audit plans?
| State | Plans audited | Share of practice |
|---|---|---|
| Minnesota | 63 | 71.6% |
| Iowa | 9 | 10.2% |
| Wisconsin | 4 | 4.5% |
| Colorado | 2 | 2.3% |
| Texas | 2 | 2.3% |
| California | 1 | 1.1% |
| Connecticut | 1 | 1.1% |
| Florida | 1 | 1.1% |
| Indiana | 1 | 1.1% |
| Kansas | 1 | 1.1% |
| Maine | 1 | 1.1% |
| Montana | 1 | 1.1% |
| North Dakota | 1 | 1.1% |
Largest concentration: Minnesota (63 plans). State reflects the plan sponsor’s address, not the firm’s office locations.
What audit opinions does Olsen Thielen & Co., LTD issue?
| Opinion type | Filings | Share |
|---|---|---|
| Unmodified (clean) | 88 | 100.0% |
| Qualified | 0 | 0.0% |
| Disclaimer | 0 | 0.0% |
| Adverse | 0 | 0.0% |
As coded on Schedule H. A disclaimer here usually reflects the legacy limited-scope reporting convention (now the ERISA Section 103(a)(3)(C) election), not a failed audit — see the methodology.
Largest plans audited by Olsen Thielen & Co., LTD
| Plan sponsor | State | Participants |
|---|---|---|
| Ecolab Inc. | MN | 35,291 |
| RBC USA Holdco Corporation | MN | 15,250 |
| Employer Solutions Group, LLC | MN | 5,222 |
| Sun Country, Inc. | MN | 3,052 |
| Hubbard Broadcasting, Inc. | MN | 2,600 |
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About this profile
This page is generated from public U.S. Department of Labor Form 5500 filings in which Olsen Thielen & Co., LTD (EIN 41-1360831) is named as the plan’s independent qualified public accountant. Olsen Thielen & Co., LTD did not supply, review, or endorse this information, and inclusion is not a recommendation. Filing data can contain sponsor-entered errors; corrections are welcome via the about page.