Tonneson & Company, PC
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 Tonneson & Company, PC audit?
Tonneson & Company, PC was the independent auditor for 22 retirement plan filings in plan year 2024, with clients in 4 states and territories — the #481 practice nationally by volume.
Practice at a glance
| Measure | Value |
|---|---|
| Firm EIN (as filed) | 04-2943536 |
| Retirement plan audits (401(k), 403(b), pension) | 22 |
| All audited filings (incl. welfare plans) | 22 |
| States and territories with clients | 4 |
| National rank by retirement plan volume | #481 of 3,956 |
| National rank, all audited filings (league-table basis) | #500 of 4,052 |
| Average client size (participants) | 518 |
| Largest client (participants) | 2,398 |
Rankings derived from U.S. Department of Labor Form 5500 filings, plan year 2024. Read the full methodology.
Where does Tonneson & Company, PC audit plans?
| State | Plans audited | Share of practice |
|---|---|---|
| Massachusetts | 19 | 86.4% |
| Arizona | 1 | 4.5% |
| New Hampshire | 1 | 4.5% |
| New York | 1 | 4.5% |
Largest concentration: Massachusetts (19 plans). State reflects the plan sponsor’s address, not the firm’s office locations.
What audit opinions does Tonneson & Company, PC issue?
| Opinion type | Filings | Share |
|---|---|---|
| Unmodified (clean) | 22 | 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 Tonneson & Company, PC
| Plan sponsor | State | Participants |
|---|---|---|
| L. Knife & Son, LLC | MA | 2,398 |
| Nouria Energy Corporation | MA | 2,016 |
| Weston & Sampson | MA | 946 |
| Millstone Medical Outsourcing, LLC | MA | 693 |
| E Ink Corporation | MA | 614 |
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About this profile
This page is generated from public U.S. Department of Labor Form 5500 filings in which Tonneson & Company, PC (EIN 04-2943536) is named as the plan’s independent qualified public accountant. Tonneson & Company, PC 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.