401(k) Plan Administration in Illinois
Illinois has 12,815 retirement plans with 25 or more participants, with about 7.3 million participants between them — and in most of them the employer is the one legally responsible for running the plan. The recordkeeper holds the money. The advisor picks the funds. Unless the plan document names someone else, the employer is the plan administrator, and that is where the fiduciary responsibility sits. Admin316 takes that role: appointed in writing as your ERISA 3(16) plan administrator and 402(a) named fiduciary, running the compliance calendar and signing and filing the Form 5500.
We are an independent ERISA administrator, working with plan sponsors since 1997. We sell no investment products and take no commissions, so we work alongside whichever recordkeeper, payroll provider and advisor an Illinois employer already uses.
Illinois retirement plans by the numbers
| Form 5500 data point, plan year 2024 | Illinois | National |
|---|---|---|
| Retirement plans with 25+ participants | 12,815 | 289,097 |
| Participants in those plans (start of plan year) | 7,339,658 | 139,715,925 |
| 401(k) plans | 11,530 (90.0%) | 89.9% |
| Plans that attached an independent auditor’s report | 3,177 (24.8%) | 22.8% |
| Filed on time using the extension | 47.2% | 46.0% |
| Filed after the deadline (including any extension) | 247 (1.9%) | 1.9% |
| New plans (effective date in 2023 or 2024) | 875 (6.8%) | 6.8% |
| Health & welfare plans with 25+ participants | 2,678 | 55,018 |
Source: U.S. Department of Labor Form 5500 and 5500-SF filings, plan year 2024 (the most recent year whose filing deadlines have all passed), retirement plans with 25 or more participants at the start of the plan year, counted once per employer ID and plan number, by the sponsor’s mailing state. Timeliness is based on each return’s original filing date; late counts include only returns the DOL has received. Compiled by Admin316 from DOL data downloaded September 30, 2026.
Illinois’s retirement mandate: Illinois Secure Choice and your 401(k)
- An Illinois employer has to act if it had at least 5 Illinois employees in every quarter of the previous calendar year, has been in business at least two years, and doesn’t offer a qualified retirement plan. It must either start a qualified plan or automatically enroll its employees in Illinois Secure Choice (820 ILCS 80).
- Employees are enrolled in a Roth IRA at a 5% default contribution. They can change the rate or opt out at any time.
- Employers that already offer a qualified plan are exempt and report that exemption to the program.
- Penalties under 820 ILCS 80/85 are $250 per employee for the first calendar year of noncompliance and $500 per employee for each later year, even if the years aren’t consecutive. The Illinois Department of Revenue assesses and collects them.
- What it means for a 401(k) sponsor: penalties are charged per employee, so a lapse in plan coverage costs a growing company more each year.
Source: Illinois State Treasurer, Secure Choice; Illinois Dept. of Revenue, Secure Choice Program Enforcement and bulletin FY2023-09; 820 ILCS 80/85. This is general information, not legal advice.
Illinois plans in the 2024 filing record
- In plan year 2024, 12,815 retirement plans with 25 or more participants, sponsored by Illinois employers, filed a Form 5500. 11,530 of them (90.0%) are 401(k) plans.
- 3,177 of those plans (24.8%) attached an independent auditor’s report to their 2024 filing (national: 22.8%). A 401(k) plan generally needs this audit once it has 100 or more participants with account balances at the start of the plan year. A plan between 80 and 120 participants can keep filing as a small plan, without an audit, if it filed that way the year before.
- 47.2% filed their 2024 return after the standard seven-month deadline but within a valid extension, which counts as on time (national: 46.0%). For a calendar-year plan, the extension moves the deadline from July 31 to October 15.
- 247 plans (1.9%) were actually late: they filed their 2024 return after the deadline, including any extension (national: 1.9%). This counts only returns the DOL has received so far.
- 875 plans (6.8%) list a plan effective date in 2023 or 2024 (national: 6.8%).
Source: U.S. Department of Labor Form 5500 data, plan year 2024.
Already sponsor a plan in Illinois? Look up your plan’s filing record in our free Form 5500 lookup, or book a 20-minute call with the fiduciary who signs the filing.
Where Illinois plans concentrate
| City (sponsor mailing address) | Retirement plans (25+ participants), plan year 2024 |
|---|---|
| Chicago | 3,438 |
| Schaumburg | 236 |
| Naperville | 223 |
| Elk Grove Village | 191 |
| Springfield | 170 |
| Aurora | 168 |
City reflects the plan sponsor’s mailing address on the Form 5500, so headquarters cities concentrate. Chicago alone accounts for about 27% of Illinois’s plans in this population.
What the filing record shows about Illinois plans
Illinois’s late-filing rate matches the national average
Of the plan-year 2024 returns the DOL has received from Illinois sponsors in this population, 247 were filed after the deadline, including the extension where one was claimed — 1.9%, the same as the national rate. Average is not the same as safe: the filings that go late are almost never the ones a sponsor expects. They come in the year a payroll system changed, an entity was added, or the person who quietly owned the calendar left. Separately, 47.2% filed after the standard deadline but by the extended deadline, which is on time, not late. DOL penalties for a late Form 5500 can run up to $2,739 per day with no cap, and the Delinquent Filer Voluntary Compliance (DFVC) Program only helps sponsors who file before the DOL contacts them.
The three findings that cost Illinois sponsors the most
Late deferral deposits — employee contributions must be deposited as soon as they can reasonably be separated from the employer’s assets. Late deposits are a prohibited transaction and one of the problems DOL investigators find most often. Missed deferral opportunities — when an eligible employee, including a long-term part-time employee, is never enrolled, the fix usually requires an employer-funded contribution. A Form 5500 that doesn’t reconcile to the trust statement — a mismatch the DOL and IRS can flag for follow-up. Most of these can be fixed voluntarily: late deposits through the DOL’s Voluntary Fiduciary Correction Program (VFCP), enrollment errors through the IRS’s Employee Plans Compliance Resolution System (EPCRS), and an inaccurate Form 5500 with an amended filing. Correcting on your own usually costs far less than correcting after an audit or investigation finds the problem.
What we take over for an Illinois plan sponsor
| Responsibility | Typical arrangement | With Admin316 |
|---|---|---|
| Named plan administrator in the document | The business owner or HR director | Admin316, appointed in writing |
| Form 5500 signature and filing | Owner signs whatever the TPA prepares | We prepare, sign and file it |
| Participant notices and disclosures | Scattered between HR, payroll and recordkeeper | Tracked and delivered on the statutory calendar |
| Eligibility, entry dates, vesting | Spreadsheet maintained by whoever is available | Monitored against the plan document each payroll |
| Compliance testing and corrections | Discovered late, corrected under pressure | Run early, corrected through EPCRS/VFCP when needed |
| Distributions, loans, QDROs, force-outs | Owner approves and hopes it matches the document | Reviewed and approved as fiduciary |
How onboarding works
1. Discovery call (20 minutes)
We go over your plan document, participant count, payroll schedule, recordkeeper and any issue you’re worried about.
2. Plan review
We read the plan document and your last two Form 5500 filings, and tell you plainly what’s out of line.
3. Appointment
A board resolution and plan amendment appoint Admin316 as your 3(16) plan administrator and 402(a) named fiduciary.
4. Ongoing administration
Payroll-cycle monitoring, notices, testing and filings, with one point of contact who answers.
Check your own plan’s filing record first
Before you talk to anyone, look up your own plan. Our free Form 5500 lookup tool shows filing dates against deadlines, participant counts and the years a plan filed late for plans across the country, Illinois included. No login, no cost.
Questions Illinois plan sponsors ask
4639 Corona Dr #26, Corpus Christi, TX 78411 · serving plan sponsors in Illinois and nationwide
Hours: Monday–Friday, 8:00 a.m.–5:00 p.m. Central
Phone: (361) 271-1211 · Independent ERISA fiduciary since 1997
