A year-end 401(k) compliance calendar is not a nice-to-have for plan sponsors – it is the difference between a clean plan year and a correction project. Most employers do not miss deadlines because they are careless. They miss them because the work sits in the seams between payroll, HR, the recordkeeper and the TPA, and nobody owns the calendar itself.
This is the sponsor-facing sequence: what has to happen in the fourth quarter, what has to happen right after the plan year closes, and what has to happen before the annual filing. Dates depend on your plan year and your document, so we describe the order and the trigger rather than pretending every plan is on the same schedule.
Why the year-end calendar is a fiduciary issue, not an HR chore
Almost every year-end item is an ERISA obligation of the plan, not a favor the payroll team does for employees. Notices have to go out because the plan design depends on them. Testing has to run because the plan’s tax-qualified status depends on it. The annual report has to be signed because a person – usually an officer of the employer – attests to it under penalty of perjury.
That is why the calendar belongs to whoever holds the administrative fiduciary role. If you have not formally assigned that role, it stays with you. Our breakdown of 3(16) vs. 3(21) vs. 3(38) vs. 402(a) covers which duties can actually be handed off and which cannot.
Phase 1: Fourth quarter – notices and data hygiene
1. Send the annual notice package
Safe harbor notices, automatic enrollment notices, qualified default investment alternative (QDIA) notices and any applicable fee disclosures generally have to reach participants a reasonable period before the start of the new plan year. The single most common failure is not the new-hire notice – it is the annual notice to everyone already in the plan. See what plan sponsors must send and when.
2. Prove delivery, not just generation
Keep the notice version, the distribution date, the recipient list and the delivery method. Proof that a notice existed is not proof it was delivered.
3. Clean the census before it becomes testing data
Fix dates of birth and hire, rehire dates, termination dates, ownership and family relationships, and compensation definitions now. Every testing problem in Phase 2 is a census problem that was left alone in Phase 1.
4. Reconcile eligibility and entry dates
Compare who the document says should be in the plan against who payroll is actually deferring for. Drift between the two is the most expensive quiet error we see – the mechanics are in 401(k) eligibility and entry dates.
5. Confirm plan design changes are documented before the year turns
If you are adding automatic enrollment, changing the match or changing eligibility, the amendment and the notice have to line up with the effective date. Deciding in December and papering it in March is how sponsors end up operating on a design their document does not support.
Phase 2: Immediately after the plan year closes – data and testing
6. Deliver a final, reconciled census
Your TPA cannot test what it cannot see. Send full-year compensation by the plan’s definition, deferrals by source, match, hours, and status changes. Late or partial census data is the number one cause of missed testing corrections.
7. Run coverage, ADP/ACP and top-heavy testing
Nondiscrimination testing determines whether refunds or corrective contributions are needed. Getting results early matters because the correction window is short and the cost rises once it closes.
8. Process corrective distributions or contributions
If testing fails, refunds to highly compensated employees or qualified contributions have to be processed on the plan’s timeline, and the amounts have to be coordinated with payroll reporting.
9. Fund employer contributions on the right schedule
Match and profit-sharing funding deadlines differ depending on whether you are chasing a deduction, a safe harbor requirement or a top-heavy minimum. Confirm which one applies to your plan rather than assuming a single date.
Phase 3: Deposits and payroll integrity – all year, reviewed at year-end
10. Tie out every payroll period to the trust
Participant deferrals must be deposited as soon as they can reasonably be segregated from general assets. Year-end is when you should compare the payroll register to the trust statement, period by period, and document any gaps. The correction path is in our guide to late deferral deposits.
11. Check loan and hardship documentation
Confirm loans are amortizing on schedule, that deemed distributions were reported, and that hardship files contain the substantiation your document requires.
12. Reconcile forfeitures
Forfeiture accounts have to be used the way the document says – and used, not parked indefinitely. An unused forfeiture balance is a standing audit question.
Phase 4: Statements, disclosures and participant-facing items
13. Issue participant statements and required disclosures
Benefit statements, annual fee disclosures and any blackout notices tied to a provider change all belong on the calendar with an owner’s name next to them.
14. Handle missing participants before distributions
Bad addresses and uncashed checks do not resolve themselves. Document the search steps you took; a search you cannot evidence is a search that did not happen.
Phase 5: The annual report and audit
15. Determine your filing and audit status
Participant counts drive whether an independent qualified public accountant’s audit is attached to the Form 5500. Counts should be confirmed from the plan’s own data, not estimated from headcount.
16. Assemble the audit file early
Plan document and amendments, adoption agreement, trust statements, payroll registers, testing results, notices, loan and distribution files, and the fidelity bond. Our 401(k) plan audit readiness checklist is the working list.
17. Review the Form 5500 before anyone signs it
The signature is an attestation. Compare participant counts, trust totals, the late-deposit question, service-provider fees and the prior-year figures before it goes out – the review sequence is in did you actually review the Form 5500 before you signed it?, and the question of who signs the Form 5500 is worth settling in advance.
18. File on time or file the extension deliberately
The annual report is due after the plan year ends, with an available extension that must be requested – not assumed. Treat the extension as a decision with an owner, not a fallback you discover in month seven.
The deadlines employers actually miss
- The annual notice to existing participants – new hires get notices; the existing population is forgotten.
- Final census delivery – sent late or incomplete, which pushes testing into the correction penalty zone.
- Corrective distributions – results arrive on time but nobody processes them.
- Deferral deposit timing during payroll disruptions – holidays, bonus runs and system conversions are where the pattern breaks.
- Amendment adoption – the plan operates on a design that was never formally adopted.
- Forfeiture use – the balance rolls forward year after year.
- Fidelity bond renewal – lapses quietly and surfaces during the audit.
Turning the calendar into a system
A calendar only works if each line has three things: a trigger, an owner and evidence. The trigger is what starts the clock (plan year end, payroll date, notice period). The owner is a named person or firm, not a department. The evidence is the artifact you would hand an auditor without searching for it.
What you can delegate, and what stays with you
A full-scope 3(16) plan administrator can own the calendar itself: notice production and delivery proof, census assembly, testing coordination, deposit monitoring, distribution and loan processing, and the annual report preparation. But providers differ enormously in how much of that they actually take – see not all 3(16) providers are the same.
What never leaves the employer: selecting and monitoring your service providers, funding the plan, deciding plan design, and transmitting accurate payroll data. You can outsource the execution; you cannot outsource the choice of who executes.
Who signs your name to the year
Here is the question worth asking before the next plan year starts: when the notices, the testing corrections and the annual report all come due, whose name is on them? Admin316 accepts the ERISA 402(a) named fiduciary appointment – the role most providers decline – and runs the year-end calendar as the responsible party, not as a reminder service.
If your calendar currently lives in one person’s head, that is worth fixing before Q4. Book a plan review with Admin316 and we will walk your plan year end to end and show you exactly which lines have no owner.
