Form 5330: The penalty tax form that HR teams discover too late

Your company has sponsored a 401(k) plan for years. Employees contribute, you provide a match, and the plan runs on autopilot. The annual audit comes back clean, participants are saving for retirement, and nobody mentions any problems.

Then your plan administrator calls with concerning news. A prohibited transaction occurred three years ago, and the excise taxes have been accumulating ever since. Or your payroll provider deposited employee deferrals a few days late every pay period, triggering penalties you never knew existed. Suddenly, you are learning about Form 5330 and wondering how much you owe.

This form reports violations of excise tax employee benefits. The penalties can be severe, and the violations that trigger them are more common than most employers realize. Understanding the Form 5330 instructions before you have a problem is far better than discovering them after years of compounding penalties.

Multiple retirement plan violations trigger excise taxes

The retirement plan excise tax system penalizes specific violations to encourage compliance. These are not income taxes. They are penalty taxes designed to deter behavior that harms plan participants or violates ERISA and tax code requirements.

1. Prohibited transactions with disqualified persons. A prohibited transaction occurs when a plan engages in certain dealings with disqualified persons, including the employer, plan fiduciaries, service providers, and family members of these parties. Common prohibited transactions include loans from the plan to the company, sales of property between the plan and the employer, and the use of plan assets to benefit the company rather than participants.

The prohibited transaction tax is steep. The initial tax is 15% of the amount involved for each year the transaction remains uncorrected. If the transaction is not corrected within the taxable period, an additional 100% tax applies. A $100,000 prohibited transaction left uncorrected for three years generates $45,000 in initial taxes plus a potential $100,000 additional tax.

2. Excess contributions that exceed limits. When contributions to a plan exceed the limits under Section 415 or when elective deferrals exceed the annual limit (currently $23,000 for 2024, plus catch-up contributions for those over 50), the excess contribution penalty applies. The excise tax is 10% of the excess amount for each year it remains in the plan.

Failed ADP and ACP testing can also create excess contributions for highly compensated employees. If corrective distributions are not made promptly, the 10% excise tax applies to the excess amounts.

3. Minimum funding failures. Defined benefit plans and money purchase pension plans have minimum funding requirements. When employers fail to contribute the required amounts, a 10% excise tax applies to the funding shortfall. If the shortfall is not corrected, an additional 100% tax applies.

This violation is less common for professional service firms, which typically sponsor 401(k) plans rather than defined benefit plans. But firms with legacy pension plans or that have acquired companies with pension obligations face this exposure.

4. Late deposits of employee deferrals. When employees defer compensation into a 401(k) plan, those deferrals must be deposited into the plan as soon as they can reasonably be segregated from the employer's assets. Department of Labor guidance creates a safe harbor of seven business days for small plans, but the legal standard is "as soon as reasonably possible."

Late deposits constitute prohibited transactions because the employer is effectively borrowing participant money interest-free. Each late deposit is a separate prohibited transaction subject to the 15% excise tax. A company that routinely deposits deferrals two weeks late has been committing prohibited transactions every pay period.

Tax rates and calculations vary by violation type

The Form 5330 instructions organize excise taxes into different schedules based on the violation type. Understanding which schedule applies determines the tax rate and calculation method.

1. Schedule A covers prohibited transactions. Report the amount involved in each prohibited transaction, the date it occurred, and whether it has been corrected. Calculate 15% of the amount involved for each year in the taxable period. If uncorrected, the 100% additional tax applies.

2. Schedule B covers excess contributions. Report excess contributions under Section 4973 with the 6% tax rate, or excess aggregate contributions from failed ADP/ACP testing under Section 4979 with the 10% rate. The tax applies annually until the excess is distributed or otherwise corrected.

3. Schedule C covers minimum funding failures. Report the accumulated funding deficiency and calculate 10% of the shortfall. If the deficiency remains uncorrected, report the 100% additional tax.

4. Schedule D covers excess fringe benefits. Certain fringe benefit plans that discriminate in favor of highly compensated employees trigger excise taxes on the excess benefits provided.

5. Other schedules cover additional violations. Form 5330 includes schedules for reversion taxes when defined benefit plans terminate with excess assets, for failures to meet minimum coverage requirements, and for other specialized situations.

Filing requirements and deadlines

Form 5330 has its own filing rules separate from your regular business tax returns.

1. The form is filed separately. Form 5330 is not part of your Form 1120 or personal tax return. It is filed independently, typically by the plan sponsor or the disqualified person who engaged in the prohibited transaction.

2. Due dates vary by violation type. For prohibited transactions, Form 5330 is due by the last day of the seventh month after the end of the tax year in which the transaction occurred. For excess contributions, the due date is typically the 15th day of the fourth month after the plan year ends. Check the specific instructions for your violation type.

3. Each violation may require a separate form. If multiple excise taxes apply, you may need to complete multiple schedules on the same Form 5330 or file separate forms depending on who is liable for each tax.

4. The plan administrator may have filing obligations. Depending on the violation, the employer, a plan fiduciary, or a disqualified person may be responsible for filing. Prohibited transaction taxes are generally paid by the disqualified person, not the plan.

Correction programs can reduce penalties

Discovering a violation does not mean you must accept the full penalty. Correction programs exist to encourage employers to fix problems.

1. The EPCRS program covers operational failures. The IRS Employee Plans Compliance Resolution System allows employers to correct many plan failures, including excess contributions and operational errors, with reduced or eliminated penalties. Self-correction is available for insignificant failures, while the Voluntary Correction Program requires an IRS submission and user fee but provides formal approval.

2. The DOL VFCP addresses prohibited transactions. The Department of Labor's Voluntary Fiduciary Correction Program allows employers to correct certain prohibited transactions, including late deferral deposits, without DOL enforcement action. Completing VFCP may also provide relief from excise taxes through a related IRS program.

3. Correction generally stops the tax from accumulating. Once a prohibited transaction is corrected, the taxable period ends, and the additional 15% tax ceases to accrue. Early correction dramatically reduces total exposure compared to letting violations continue.

4. Self-correction before audit discovery provides the best outcome. Plans that identify and correct violations before an IRS or DOL examination offer more correction options and typically pay lower penalties than those discovered during an audit.

Prevention is more cost-effective than correction

The excise taxes reported on Form 5330 are entirely avoidable with proper plan administration.

1. Timely deposit employee deferrals. Establish a payroll process that deposits 401(k) contributions within a few days of payroll, well within the seven-day safe harbor. Late deposits are the most common prohibited transaction and the easiest to prevent.

2. Monitor contribution limits. Track deferrals against annual limits and project highly compensated employee contributions to anticipate ADP/ACP testing issues. Correct excess contributions before the correction deadline.

3. Review transactions with disqualified persons. Before the plan engages in any transaction with the employer, a fiduciary, or a service provider, analyze whether it could constitute a prohibited transaction. Most prohibited transactions can be restructured or avoided entirely with planning.

4. Conduct annual compliance reviews. A proactive review of plan operations identifies issues when they are small and correctable rather than after years of accumulation.

The excise taxes on employee benefit plans exist to protect participants by penalizing violations. Employers who understand these rules and monitor compliance avoid the unpleasant surprise of discovering Form 5330 after the penalties have already grown substantial.