IRS Accuracy-Related Penalty: Essential Guide

What the IRS Accuracy-Related Penalty Means for You

The IRS accuracy-related penalty can add a serious financial hit on top of any taxes you already owe — often 20% or more of the underpaid amount.

Here’s what you need to know at a glance:

This penalty doesn’t require intent. You can face it simply for making careless mistakes on your return — like missing income on a Form 1099 or claiming a deduction you couldn’t fully support.

The Taxpayer Advocate Service’s 2018 report reviewed 120 opinions issued from June 1, 2017, through May 31, 2018. The IRS prevailed in full in 72% of those cases. That historical sample does not predict an individual taxpayer’s outcome or establish that representation caused a better result.

This guide explains exactly how the penalty works, what triggers it, how to defend against it, and what steps to take if you’ve already received a notice.

Review the relevant notices, filing history, records, and deadlines before choosing a response. Evaluate professional assistance according to the facts, applicable law, and agreed scope of representation.

Penalty overview: Negligence, substantial understatements and specified valuation or disclosure failures can trigger accuracy-related penalties. The ordinary rate is 20% of the covered underpayment, with 40% for specified categories. Reasonable cause and good faith may provide relief only where the statute permits. The tables and discussion explain the requirements.

IRS accuracy related penalty terms to know:

• IRS Tax Penalties
• IRS penalty waiver request
• IRS penalty taxpayer advocate

Understanding the IRS Accuracy Related Penalty and Its Triggers

The IRS accuracy related penalty under Internal Revenue Code (IRC) § 6662 applies to specified portions of tax underpayments. Unlike the civil fraud penalty, it does not require proof of fraud. The IRS must establish the applicable statutory ground, such as negligence or a substantial understatement; an arithmetic error alone does not automatically establish every element of the penalty.

According to the official Accuracy-related penalty | Internal Revenue Service page, the ordinary rate is 20% of the portion of the underpayment subject to the penalty. Negligence and substantial understatement penalties do not stack on the same portion to produce 40%. Separate statutory grounds can carry higher rates, as explained below.

To learn more about how this charge fits into the broader tax landscape, check out our IRS Tax Penalties Complete Guide.

Negligence vs. Disregard of Rules or Regulations

The IRS draws a thin but important line between negligence and the disregard of rules or regulations:

• Negligence: This is defined as any failure to make a reasonable attempt to comply with the provisions of the tax code or to exercise ordinary and reasonable care in preparing a tax return. It also includes a failure to keep adequate books and records or to properly substantiate items. A classic example of negligence is completely failing to report income that was clearly documented on an information return like a Form 1099 or Form W-2.
• Disregard of Rules or Regulations: This occurs when a taxpayer carelessly, recklessly, or intentionally ignores the tax laws, Treasury regulations, or IRS revenue rulings. For example, if you are aware of a specific tax regulation that explicitly forbids a certain deduction, but you claim it anyway without a reasonable basis, you have disregarded the rules.

Common real-world triggers for negligence penalties include claiming deductions or credits that are “too good to be true” without verifying their legitimacy, keeping highly disorganized records (or no records at all), and failing to check your tax return for obvious errors before signing it.

Substantial Understatement of Income Tax

An IRS accuracy related penalty for substantial understatement under IRC § 6662(b)(2) can apply without negligence when the statutory threshold is exceeded. The calculation must account for applicable reductions, including qualifying substantial-authority positions or adequate disclosure with a reasonable basis, subject to tax-shelter restrictions. Available defenses and procedural requirements still matter; the result is not automatic merely because the IRS proposes additional tax.

The thresholds under 26 U.S. Code § 6662 – Imposition of accuracy-related penalty on underpayments depend on the taxpayer category and applicable deduction rules:

• Individuals: A substantial understatement exists if the understatement exceeds the greater of 10% of the tax required to be shown on the return or $5,000.
• Section 199A QBI Deduction Impact: If you claim the Qualified Business Income (QBI) deduction under Section 199A, the threshold for individuals is lowered to 5% of the tax required to be shown or $5,000, whichever is greater. This makes it much easier for small business owners and self-employed individuals to accidentally trigger the penalty.
• Corporations: For C corporations (other than S corporations or personal holding companies), a substantial understatement occurs if the understatement exceeds the lesser of 10% of the tax required to be shown (or, if greater, $10,000) or a flat $10,000,000.

How the Penalty is Calculated and When It Increases to 40%

Calculating the IRS accuracy related penalty is relatively straightforward but financially painful. The penalty is applied directly to the portion of the underpayment that is deemed inaccurate. For example, if an audit reveals you owe an additional $30,000 in back taxes, and the IRS determines that $20,000 of that shortfall was due to negligence, your penalty will be 20% of $20,000, which equals $4,000.

However, under certain circumstances, the penalty rate doubles from 20% to 40%. This harsher rate applies to:

• A gross ordinary property or adjusted-basis valuation misstatement generally occurs at 200% or more of the correct amount. Gross estate and gift valuation misstatements generally occur at 40% or less of the correct value; 65% is the substantial, rather than gross, threshold. Separate thresholds apply to transfer pricing and pension liabilities, and minimum underpayment amounts and other statutory conditions must also be met.
• Undisclosed Foreign Financial Assets: A 40% rate applies to the portion of an underpayment attributable to a qualifying undisclosed foreign financial asset understatement under IRC § 6662(j). The definition concerns missing information required under specified Internal Revenue Code provisions, including §§ 6038 and 6038D; an FBAR violation alone does not automatically establish this penalty.
• Nondisclosed Noneconomic Substance Transactions: A 40% rate applies to the portion of an underpayment attributable to a transaction lacking economic substance under the applicable rule when the relevant tax-treatment facts were not adequately disclosed. Adequate disclosure generally leaves a 20% rate for that ground; reasonable cause is not a defense to this statutory category.

Interest generally accrues daily on unpaid tax and applicable penalties until payment. Tax interest ordinarily starts at the original payment due date; for accuracy-related penalties, the IRS identifies the return due date, including a valid filing extension, as the relevant start date. Different penalties can have different interest start dates. See IRS Interest Accrual and Abatement.

Defending Against the Penalty: Reasonable Cause and Good Faith

Reasonable cause and good faith under IRC § 6664(c) can protect the applicable portion of an underpayment, but the defense has statutory limits. It is unavailable for transactions lacking economic substance and deductions disallowed under IRC § 170(h)(7). It also generally does not protect substantial or gross charitable-property valuation overstatements; a substantial overstatement may qualify only with a qualified appraisal by a qualified appraiser and a good-faith investigation of value.

The IRS evaluates reasonable cause on all relevant facts and circumstances, including the effort to determine the correct tax, the issue’s complexity, and the taxpayer’s education and experience. A reasonable misunderstanding can support relief, but honest intent or an accidental oversight does not by itself guarantee that the requirements are met.

If you are facing an audit assessment, you can explore strategies to Reduce IRS Tax Penalties by demonstrating your honest intent to comply.

Reasonable Reliance on a Tax Professional or Software

Many taxpayers assume that simply hiring a CPA or using professional tax software automatically protects them from penalties. Unfortunately, it is not that simple. To successfully claim reasonable cause based on professional advice, the courts use a strict three-part test (established in the landmark case Neonatology Associates, P.A. v. Commissioner):

1. Competence of the Adviser: The tax professional must have had sufficient expertise and knowledge in the specific area of tax law to justify your reliance.
2. Full and Accurate Information: You must have provided the adviser with all necessary, accurate, and complete financial records and information. If you hid income or lied to your CPA, this defense is instantly destroyed.
3. Actual Good Faith Reliance: You must have actually relied on the professional’s advice in good faith. If the advice was so outrageous or “too good to be true” that a reasonable person would have questioned it, the IRS will reject your defense.

Tax preparation software does not automatically establish reasonable cause. Incorrect inputs, unsupported classifications, and warnings that were ignored must be evaluated with the taxpayer’s other efforts to determine the correct liability. Keep records of the information entered and any advice sought.

Documentation and Record-Keeping Best Practices

Support a reasonable-cause request with records that explain what happened and the efforts made to comply. Good documentation helps establish the facts but does not guarantee relief or Avoid IRS Penalties in every case. Useful practices include:

• Maintaining contemporaneous logbooks for business travel, mileage, and meals.
• Keeping all receipts, invoices, bank statements, and canceled checks organized by tax year.
• Documenting any written communications or advice received from your tax preparer.
• Storing digital copies of your records in a secure, backed-up cloud environment to prevent loss due to natural disasters or physical damage.

IRS Procedures: Automatic Assertions and Disputing the Penalty

In recent years, the IRS has increasingly relied on automated systems like the Automated Underreporter (AUR) to match tax returns against third-party data (such as Forms W-2 and 1099). When a mismatch is found, these systems often automatically propose an IRS accuracy related penalty alongside the tax adjustment.

IRC section 6751(b) generally requires written supervisory approval of covered penalty determinations, subject to exceptions. Approval timing and the consequences of a defect depend on the applicable rules, jurisdiction, and case facts. Do not assume that every penalty lacking approval before a deficiency notice must be dismissed.

For a deeper look into how these procedural battles play out in audits, you can review the National Taxpayer Advocate’s report on the Accuracy-Related Penalty Under IRC § 6662(b)(1) and (2).

How to Dispute an IRS Accuracy Related Penalty

If you receive an IRS notice proposing an accuracy penalty, do not panic. You have clear administrative pathways to challenge the decision:

1. Submit a Written Explanation: Respond to the examiner or address on the notice by its stated deadline. A proposed-adjustment letter may allow 30 days, while other notices have different rules. Include a signed explanation and supporting documents. A penalty-relief request does not extend a Tax Court petition deadline stated in a notice of deficiency.
2. Check the Correct Refund or Abatement Procedure: Form 843 can request abatement or refund of eligible penalties. Follow its instructions and the applicable claim deadline. It is not a substitute for an amended income-tax return when that is required, and it does not extend a Tax Court deadline.
3. Request an IRS Appeals Hearing: If the auditor rejects your initial defense, you have the right to take your case to the IRS Office of Appeals. This independent body has the authority to settle disputes based on the “hazards of litigation” (the likelihood that the IRS might lose if the case went to court).

For step-by-step guidance on crafting a compelling defense, follow our guide on How to Request an IRS Penalty Waiver in 5 Easy Steps.

Key Differences: Accuracy-Related Penalty vs. Fraud Penalty

It is crucial to understand the difference between a mistake and intentional deception. The IRS separates these behaviors into two distinct statutory penalties:

• Accuracy-Related Penalty (IRC § 6662): Generally 20% of the covered portion, with higher rates for specified grounds. Negligence, substantial understatement and other statutory categories have distinct requirements; fraud need not be proved. The applicable burden of production or proof depends on the issue and proceeding.

• Civil Fraud Penalty (IRC § 6663): 75% of the portion attributable to fraud. The IRS must establish fraud by clear and convincing evidence. Once it establishes fraud for part of the underpayment, the taxpayer must show which remaining portion is not attributable to fraud. Examples may include deliberately concealed income or fabricated deductions.

• Possible Negligence: Omitting income shown on Form 1099-NEC can indicate negligence. Moving and not receiving the form does not eliminate the duty to report income, but the full facts and any available reasonable-cause defense must be considered.

• Fraud: Operating an all-cash business and intentionally keeping a secret bank account to hide hundreds of thousands of dollars in revenue from your tax preparer.

Frequently Asked Questions About the IRS Accuracy Related Penalty

What triggers an IRS accuracy related penalty?

The penalty can apply to an underpayment attributable to negligence, disregard of rules, substantial understatement, or another specified statutory ground. For individuals, the ordinary substantial-understatement threshold is more than the greater of 10% of the required tax or $5,000; the percentage becomes 5% for a taxpayer claiming a section 199A deduction. Applicable reductions, exceptions and defenses must also be considered.

Can I get an accuracy-related penalty waived with First-Time Abatement?

No. First-Time Abatement and the IRS’s Automatic Exemption from Penalty program introduced in summer 2026 address specified filing, payment and deposit penalties; they do not cover the accuracy-related penalty. Potential grounds to contest an accuracy penalty include an incorrect underlying adjustment, failure to meet the statutory ground, qualifying substantial-authority or disclosure rules, reasonable cause where permitted, or an applicable procedural defect. See our IRS Penalty Abatement Complete Guide.

What is the success rate for taxpayers disputing this penalty in court?

The Taxpayer Advocate Service’s 2018 report identified 120 opinions issued from June 1, 2017, through May 31, 2018, involving accuracy-related penalties. In that historical set:

• The IRS prevailed in full in 86 cases (72%).
• Taxpayers prevailed in full in 29 cases (24%).
• There were 5 split decisions (4%).

The reported historical comparison of represented and unrepresented cases does not establish any individual taxpayer’s chances or show that representation caused the difference. Outcomes depend on the facts, law, procedure and evidence.

Conclusion

An IRS accuracy related penalty requires careful analysis of the adjustment, statutory thresholds, available defenses and procedural deadlines. Professional assistance may help with complex disputes; it does not guarantee removal of the penalty or a particular result.

Review the relevant notices, filing history, records, and deadlines before choosing a response. Evaluate professional assistance according to the facts, applicable law, and agreed scope of representation.

Contact us today to schedule a professional consultation and protect your financial future. Learn more about how we can support you by visiting our IRS Penalty Abatement Services page.