Late 401(k) Deposits: How to Calculate Lost Earnings and Correct the Failure

Late 401(k) deposits require a documented identification, correction, lost-earnings calculation, and process repair—not simply moving the withheld cash into the trust after the fact.

A late deposit can look small on a cash report, but it involves participant money and a missed investment period. The corrective file should be built from dates and evidence, not from an estimate in an email. Start by identifying each late payroll and the earliest date the amounts could have been segregated.

Define the operating question

The IRS fix-it guide instructs sponsors to compare the earliest segregation date with actual deposit dates and to deposit late elective deferrals and resulting earnings into the trust.[1] It also notes that DOL’s Voluntary Fiduciary Correction Program may be relevant. The DOL online calculator is designed to compute lost earnings and related amounts for VFCP work, but the DOL cautions that using the calculator alone does not fulfill all correction requirements.[2]

Before reviewing individual transactions, write the question in a way that can be tested: which people, pay periods, contribution source, and plan provisions are in scope? Use source-system extracts with an “as of” date and preserve the version of the plan materials used. That discipline separates a defensible finding from a report that merely looks complete.

Compare records before drawing a conclusion

Principal is the amount withheld but not timely deposited. Lost earnings are the plan’s economic loss from the delayed funding. A correction calculation is not a penalty estimate and it is not interchangeable with a simple interest spreadsheet; the facts, applicable program requirements, and plan records matter.

Use a variance log that records the participant or payroll population, source records, initial explanation, owner, due date, and disposition. Do not silently overwrite a difference to make totals agree. A documented “not an error” conclusion is valuable because it shows why the reviewer rejected the exception.

Make the comparison reproducible. Save the original extract names, filters, report dates, and calculation version, then have another reviewer rerun a small sample from the same evidence. This is especially important when a payroll code, job classification, or plan amendment changes during the review period. A control is more reliable when it can explain both a matched item and an exception. Where information is incomplete, label the item as pending rather than guessing an effective date or contribution source. The resulting file gives the sponsor a practical audit trail and a clearer handoff if outside counsel or a plan specialist needs to evaluate a potential correction.

Implement a controlled response

Once a variance is confirmed, contain the issue first. Stop the faulty configuration or manual process, preserve the records, and identify whether additional payrolls or populations use the same rule. Then use a consistent case file: facts, governing terms, analysis, professional advice, corrective amounts if applicable, approvals, funding evidence, participant communications, and prevention steps. The right sequence depends on the plan and facts, so administrators should involve ERISA counsel, a qualified TPA, or other appropriate advisers before selecting a correction method.

1. Create a payroll-level inventory with participant amounts, pay date, earliest segregation date, actual deposit date, and supporting records.
2. Deposit outstanding principal immediately after confirming the amounts.
3. Engage the appropriate administrator, counsel, or correction professional to select the correction path and calculate lost earnings.
4. Use the DOL’s VFCP tools where applicable and retain calculation inputs, outputs, approvals, and proof of funding.
5. Document the root cause—such as approval delay, interface failure, or cash-control breakdown—and implement a tested prevention control.

Assign one owner for the case, but do not make that person the only reviewer. Payroll can validate source data, HR can validate employment events, and the recordkeeper can validate posting. The plan administrator should retain the final decision trail. This division makes it easier to distinguish a data correction from a plan-operation correction and reduces the risk that a fix in one system is never reflected in another.

Review the control, not only the case

Verify that every affected payroll is included, every affected participant allocation is accounted for, and the trust has received both principal and any required corrective amount. The final review should also address required filings, notices, or program steps with qualified advisers. Repeat the timing reconciliation for several cycles to demonstrate that the control repair works.

Practical review table

Close the review by asking whether the control would detect the same failure next month. If the answer depends on a person remembering a special step, convert that step into an owned report, a documented approval, or a system validation. Retain both the original exception and the proof of the changed process. Periodic samples should confirm that the control is operating in practice, not merely written into a procedure.

Editorial disclaimer: This article is general educational information, not legal, tax, investment, actuarial, or compliance advice. Plan documents, facts, and current guidance can change the result; consult qualified advisers before acting.

Educational information only; not tax, legal, actuarial, investment, or compliance advice. Plan documents, current law, and qualified professional review control any decision.

References

• [1] https://www.dol.gov/agencies/ebsa/employers-and-advisers/plan-administration-and-compliance/correction-programs/vfcp/calculator
• [2] https://www.irs.gov/retirement-plans/401k-plan-fix-it-guide-you-have-not-timely-deposited-employee-elective-deferrals