When a Form 5500 large-plan audit becomes mandatory
Plans with 100+ participants at the start of the plan year file as 'large' plans and must attach an independent audit opinion to Schedule H. The 80–120 rule preserves the prior-year filing status near the threshold. The check below tells you which side of the line you're on this year.
The 100-participant threshold
A plan is “large” for Form 5500 reporting purposes if it had 100 or more participants at the beginning of the plan year. Large plans file Schedule H (large-plan financial information) and must attach an opinion from an independent qualified public accountant (IQPA). Plans below 100 file Schedule I and don't attach an audit opinion.
The participant count is taken at the beginning of the plan year, not the end. A plan that grew through the year into the 100-plus band files small for that year and large for the following year (subject to the 80–120 cushion below).
The 80–120 cushion (carry-forward rule)
When a plan filed as small the prior year, it can continue filing as small if the participant count at the start of the current plan year is between 80 and 120. The plan only crosses into large- plan filing once the count exceeds 120 at the start of a plan year. This cushion exists so a plan that drifts across the 100- participant line year-to-year doesn't trigger an audit- opinion engagement for a single year.
The cushion only goes one direction: small → small. A plan that filed as large the prior year continues filing as large until the participant count drops below 100 at the start of a year. There is no 80–120 cushion working from large back down to small.
Does the plan need an IQPA audit opinion this year?
With 110 participants and a small-plan filing in the prior year, the 80–120 rule preserves small-plan status this year (the participant count is above 100, but within the cushion). No audit opinion required.
The participant count rule and the 80–120 cushion apply at the start of the plan year, not the end. For welfare plans funded entirely through a §125 cafeteria-plan unfunded structure, additional rules may waive the audit-opinion requirement; confirm with ERISA counsel.
Welfare plans funded entirely through unfunded §125 arrangements
Some welfare plans funded entirely through §125 cafeteria-plan unfunded arrangements may be exempt from the audit-opinion requirement under specific DOL guidance. The exemption is narrow and depends on the plan's asset structure. Confirm with ERISA counsel before relying on the exemption — a misclassified plan that should have attached an audit opinion is treated as a delinquent filing.
What the audit opinion costs (and why it matters)
Plan audits typically cost $7,500–$25,000 for mid-market sponsors, depending on plan size, complexity, and prior audit findings. The opinion is filed publicly with Schedule H, and the type of opinion (unqualified, qualified, adverse, or disclaimer) is part of the public record. A “qualified” opinion — the auditor could not satisfy themselves on some specific scope — is itself a recurring fiduciary-review flag.
BenefitsLedger surfaces the audit-opinion type as a factor in the Fiduciary Fitness Audit when present in the public record.
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- DOL Form 5500 Instructions — Schedule H, audit-opinion requirement — DOL EBSA landing page; current-year Form 5500 instructions linked from the EFAST2 portal.
- 29 CFR 2520.103-1 — Annual reporting; large/small plan rules — DOL regulation establishing the 100-participant threshold for the audit-opinion attachment.
- AICPA — Employee Benefit Plan Audit Quality Center — Standards and guidance for the independent qualified public accountant (IQPA) opinion.