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. Numetix runs expert-led, AI-powered, human-in-the-loop payroll and compliance support for service firms, including deferral deposit timing controls that prevent the most common Form 5330 trigger before it starts.

This form reports violations of excise tax on 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.

Which retirement plan violations trigger Form 5330 excise taxes, and which ones are most commonly missed?

Four violation types: prohibited transactions with disqualified persons (loans from the plan to the company, property sales between plan and employer, use of plan assets for company benefit), excess contributions, minimum funding failures for defined benefit and money purchase pension plans, and late deposits of employee deferrals. Late deposits are the most common because a two-week delay every pay period is a separate prohibited transaction each time. 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 ($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.

How do the Form 5330 tax rates and schedules work, and which schedule applies to your situation?

Schedule A covers prohibited transactions (15% of the amount involved per year, 100% if uncorrected). Schedule B covers excess contributions (6% under Section 4973 or 10% under Section 4979 for failed ADP/ACP testing). Schedule C covers minimum funding failures (10% of the shortfall, 100% if uncorrected). Schedule D covers excess fringe benefits. Each schedule has a separate rate structure and calculation method. 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.

What are the Form 5330 filing requirements, and when is each type of violation due?

Form 5330 is filed separately from your business return. For prohibited transactions, it 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, it is due on the 15th day of the fourth month after the plan year ends. Multiple violations may require multiple schedules or separate filings depending on who is liable. 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.

Can excise tax penalties be reduced after the fact, and what correction programs are available?

Yes. The IRS EPCRS covers many operational failures including excess contributions, with self-correction available for insignificant failures and the Voluntary Correction Program for formal IRS approval. The DOL VFCP addresses prohibited transactions including late deposits and may provide IRS excise tax relief through a separate submission. Both produce far better outcomes than violations discovered during an audit. 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 have more correction options and typically pay lower penalties than those discovered during an audit.

What four practices prevent Form 5330 excise taxes before they accumulate?

Deposit employee deferrals within the seven-business-day safe harbor (the most preventable violation), monitor contribution limits and project highly compensated employee deferrals before ADP/ACP testing, review any planned transaction with a disqualified person before it occurs, and conduct an annual compliance review to catch small issues before they compound into multi-year penalty exposure. 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.

Frequently asked questions

How far back can the IRS assess Form 5330 excise taxes?

The statute of limitations is generally three years from the filing date, or six years for a substantial understatement. However, because prohibited transactions generate a new 15% excise tax for each year the violation remains uncorrected, the exposure grows continuously until the transaction is corrected and the form is properly filed for each open year.

Who is responsible for paying the Form 5330 excise tax?

Responsibility depends on the violation type. Prohibited transaction taxes are paid by the disqualified person who engaged in the transaction, not the plan itself. Excess contribution and minimum funding excise taxes are typically the employer's obligation. The plan administrator may have separate filing obligations from the party actually responsible for paying the excise tax.

Does completing the DOL VFCP eliminate the Form 5330 excise tax on late deposits?

Not automatically. VFCP completion can provide IRS excise tax relief on late deferral deposits, but only through a separate no-action letter submission to the IRS. Employers who complete the DOL correction without requesting the related IRS relief may still owe Form 5330 excise taxes on the late deposits even after DOL acceptance of the correction.