ERISA Plan Number 501 and Form 5500: Deadlines, Penalties, and Fixes

On a Form 5500 or a benefits document, plan number 501 is the three-digit identifier a plan sponsor assigns to its first welfare benefit plan under the Employee Retirement Income Security Act of 1974. Welfare plans (group health, dental, vision, life, disability, and similar coverage) start their numbering at 501; a sponsor’s second welfare plan gets 502, the third 503, and so on. Pension and retirement plans use a separate series that starts at 001. Combined with the employer’s nine-digit EIN, the three-digit plan number forms a 12-digit identifier that the Department of Labor, IRS, and Pension Benefit Guaranty Corporation use to track the plan across its entire lifespan.¹

So if the number on your paperwork begins with a 5, you are looking at a welfare plan, not a retirement plan. That distinction drives everything that follows: which form gets filed, which schedules attach, whether an audit is required, and whether the plan even has to file at all.

How Sponsors Assign the Number

The sponsor assigns the plan number, not the government. You pick it when you file the plan’s first annual report, following the DOL’s numbering convention: 501 for the first welfare plan, incrementing by one for each additional welfare plan the same employer maintains.¹

Once assigned, the number is permanent. You keep using it on every annual filing for as long as the plan exists, and you cannot reassign it to a different plan even after the original terminates.¹ That permanence is what lets regulators trace a plan’s history across decades of filings.

ERISA itself does not reach every benefit plan. Government employee plans, church plans, workers’ compensation plans, and plans maintained outside the United States primarily for nonresident aliens fall outside the statute. Sponsors of those plans do not assign a 501-series number because ERISA’s reporting rules do not apply to them.²

Does a 501 Plan Actually Have to File Form 5500?

Not always. A welfare plan with fewer than 100 participants is exempt from the annual Form 5500 filing requirement if it meets one of two conditions: benefits come directly from the employer’s general assets (an unfunded plan), or benefits are provided entirely through insurance contracts with premiums paid by the employer. A combination of both also qualifies.³

This exemption covers a large share of small employers whose group health coverage is fully insured through a carrier. If your plan qualifies, you still use the 501 designation for internal tracking, but the annual filing obligation drops away. Once your plan hits 100 participants at the beginning of the plan year, or is funded in a way that falls outside the exemption, the Form 5500 requirement kicks in.

What the Form 5500 Filing Involves

Form 5500 is the annual return most ERISA-covered plans file to report financial condition, investments, and operations. The DOL, IRS, and PBGC jointly developed it so plans can satisfy annual reporting requirements under both ERISA and the Internal Revenue Code in a single filing.⁴ The form asks for the plan’s 12-digit identifier, so the 501 (or 502, 503, and so on) sits alongside the EIN at the top of every return.

Plans with fewer than 100 participants may qualify to file Form 5500-SF, a shorter version with fewer schedules.⁴

Schedule A for Insured Benefits

Welfare plans that provide benefits through insurance contracts must attach Schedule A. It reports premiums paid to the carrier, commissions and fees paid to brokers or agents, claims paid, and any dividends or retroactive rate refunds. For experience-rated contracts, Schedule A also breaks out retention charges such as administrative fees, taxes, and acquisition costs.

Audit for Large Plans

Plans with 100 or more participants at the beginning of the plan year generally must include a report from an independent qualified public accountant with the filing. The audit examines the plan’s financial statements and internal controls, and the cost falls on the plan or the employer. Staying under the 100-participant threshold avoids the requirement entirely.

Electronic Filing

All Form 5500 filings must be submitted electronically through the ERISA Filing Acceptance System (EFAST2). Paper filings are not accepted. Filers can use the government’s free online tool (IFILE) or purchase EFAST2-approved third-party software.⁵

When the Filing Is Due

Form 5500 is due by the last day of the seventh month after the plan year ends. For calendar-year plans, that means July 31.⁴

Filing IRS Form 5558 before the original deadline automatically extends the due date by two and a half months, pushing a calendar-year plan to October 15.⁶ The extension is automatic when the form is complete and filed on time. There is no approval letter.

Penalties for Late or Missing Filings

Two agencies can penalize the same delinquent filing.

The IRS charges $250 per day for each day a Form 5500-series return is late, up to $150,000 per return. This penalty applies to returns required to be filed after December 31, 2019, under the SECURE Act.⁴

The DOL has a separate civil penalty under ERISA Section 502(c)(2). The statutory base is up to $1,000 per day, adjusted annually for inflation, and currently exceeds $2,500 per day.⁷ The DOL considers the degree of willfulness when setting the actual amount. Because the two agencies act independently, a single missed Form 5500 can generate combined penalties that reach tens of thousands of dollars quickly.

Fixing a Missed Filing

If you realize a Form 5500 is missing, the DOL’s Delinquent Filer Voluntary Compliance Program (DFVCP) sharply reduces the civil penalty. You must not have already received a notice of intent to assess a penalty for the missing filing.⁸

Under DFVCP, the penalty is $10 per day, with the following caps:

Small plans (fewer than 100 participants): $750 per filing, $1,500 per plan total. Plans sponsored by 501(c)(3) tax-exempt organizations have a $750 per-plan cap.
Large plans (100 or more participants): $2,000 per filing, $4,000 per plan total.

A filing that could otherwise trigger over $100,000 in combined penalties can be resolved for $750 to $2,000 through the program.⁸

When a sponsor uses DFVCP, the IRS generally will not pursue its own late-filing penalties, provided certain conditions are met.⁹ One-participant plans that file Form 5500-EZ are not eligible for DFVCP, but the IRS runs a separate relief program for them with a flat fee of $500 per delinquent return, up to $1,500 per submission.¹⁰

The Summary Annual Report to Participants

Filing Form 5500 satisfies the government side of the disclosure. There’s a participant side too. Plans must distribute a Summary Annual Report (SAR) to every participant and to beneficiaries receiving benefits. The SAR is a condensed, plain-language version of the annual report.

The SAR must be furnished within nine months after the close of the plan year. If the plan received an extension to file Form 5500, the SAR deadline extends to two months after the extended filing period ends.¹¹ Welfare plans exempt from Form 5500 under the small-plan exemption are also exempt from distributing a SAR.

1
Department of Labor. 2025 Instructions for Form 5500 Annual Return/Report of Employee Benefit Plan
2
Office of the Law Revision Counsel. 29 USC Ch. 18 – Employee Retirement Income Security Program
3
eCFR. 29 CFR 2520.104-20 – Limited Exemption for Certain Small Welfare Plans
4
Internal Revenue Service. Form 5500 Corner
5
U.S. Department of Labor. FAQs on EFAST2 Electronic Filing System
6
Internal Revenue Service. Form 5558 – Application for Extension of Time to File Certain Employee Plan Returns
7
eCFR. 29 CFR 2560.502c-2 – Civil Penalties Under Section 502(c)(2)
8
U.S. Department of Labor. Delinquent Filer Voluntary Compliance Program
9
Internal Revenue Service. 401(k) Plan Fix-It Guide – You Haven’t Filed a Form 5500 This Year
10
Internal Revenue Service. Penalty Relief Program for Form 5500-EZ Late Filers
11
eCFR. 29 CFR 2520.104b-10 – Summary Annual Report