IRS Accuracy-Related Penalty Explained
The accuracy-related penalty under Internal Revenue Code §6662 imposes a 20% penalty on underpayments attributable to negligence, substantial understatement of tax, valuation misstatements, or pension liability overstatements. For gross valuation misstatements, the penalty rises to 40%. Here is what triggers the penalty, how the IRS assesses it, and the defenses that can eliminate it.
This article is for educational purposes only. Penalty eligibility, defenses, and outcomes depend on individual facts and IRS rules. Results vary.
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What the Accuracy-Related Penalty Is
The accuracy-related penalty under IRC §6662 is one of the most frequently assessed penalties in the IRS arsenal. It is a 20% penalty applied to the portion of any underpayment of tax that is attributable to one or more specific statutory grounds. Unlike the failure-to-file or failure-to-pay penalties — which accrue over time — the accuracy-related penalty is assessed as a flat percentage of the underpayment and is added in a single assessment. It is imposed on top of the tax itself and on top of any interest that has accrued, which means it can dramatically increase the total amount you owe.
The policy rationale is straightforward: the tax system relies on taxpayers reporting their income, deductions, and credits accurately. When a taxpayer takes a position that understates their tax liability by a meaningful amount — or when the return reflects negligence or disregard of the rules — the penalty is designed to discourage that behavior and to compensate the government for the administrative burden of identifying and correcting the error. The penalty is civil, not criminal — but the financial impact can be severe.
The accuracy-related penalty interacts with other penalties in important ways. If multiple accuracy-related penalties apply to the same underpayment (for example, both negligence and substantial understatement), the penalty is assessed only once at 20% — the penalties do not stack on top of each other. However, the accuracy-related penalty stacks with the fraud penalty under IRC §6663 if fraud is also present, and it can be assessed alongside failure-to-file and failure-to-pay penalties.
The Four Statutory Grounds for the Penalty
IRC §6662 identifies four distinct grounds on which the accuracy-related penalty may be imposed. The IRS must specify which ground (or grounds) it is relying on. Each ground has specific definitions, thresholds, and defenses.
Negligence or Disregard of Rules or Regulations (§6662(b)(1))
Negligence includes any failure to make a reasonable attempt to comply with the tax laws — failing to keep adequate books and records, failing to substantiate items properly, or claiming deductions without a reasonable basis. Disregard of rules means carelessly, recklessly, or intentionally ignoring IRS regulations or revenue rulings. The IRS does not need to prove intent — a pattern of sloppy recordkeeping or a claim that a reasonable person would know is unsupported is enough. This is often the easiest ground for the IRS to assert.
Substantial Understatement of Income Tax (§6662(b)(2) and §6662(d))
A substantial understatement exists when the amount of the understatement exceeds the greater of 10% of the tax required to be shown on the return, or $5,000. For corporations (other than S corporations and personal holding companies), the threshold is the lesser of 10% of the tax required to be shown (or $10,000 if greater) or $10,000,000. The understatement is reduced by any portion attributable to a position for which there was substantial authority, or a position that was adequately disclosed on the return and had a reasonable basis.
Substantial Valuation Misstatement (§6662(b)(3) and §6662(e))
A substantial valuation misstatement exists when the value or adjusted basis of property claimed on the return is 150% or more of the correct amount. For certain charitable deduction property and estate/gift tax valuations, the threshold is lower. This ground commonly arises in cases involving inflated charitable contribution deductions, overstated basis in sold property, and aggressive estate/gift valuations. The penalty increases to 40% when the misstatement is gross — meaning 200% or more of the correct value.
Substantial Overstatement of Pension Liabilities (§6662(b)(4) and §6662(f))
This ground applies specifically to employers who substantially overstate their pension liabilities for purposes of computing deductible contributions. A substantial overstatement exists when the actuarial determination of pension liabilities is 200% or more of the correct amount. This is the least common ground for the accuracy-related penalty and primarily affects defined benefit pension plan sponsors.
How the Penalty Is Calculated: 20% and 40% Rates
The standard accuracy-related penalty rate is 20% of the underpayment that is attributable to the qualifying conduct. The "underpayment" is generally defined as the amount of tax that should have been reported on the return minus the amount actually reported (after taking into account any rebates). If the underpayment is $50,000, the penalty is $10,000 — on top of the $50,000 in back taxes and any accumulated interest.
Penalty Rate Comparison
| Situation | Rate | Trigger |
|---|---|---|
| Negligence | 20% | Any underpayment due to negligence or disregard of rules |
| Substantial Understatement | 20% | Understatement exceeds 10% of correct tax or $5,000 |
| Substantial Valuation Misstatement | 20% | Claimed value is 150%+ of correct value |
| Gross Valuation Misstatement | 40% | Claimed value is 200%+ of correct value |
| Pension Liability Overstatement | 20% | Claimed liability is 200%+ of correct amount |
| Transaction Lacking Economic Substance | 40% | Noneconomic substance transaction (no reasonable cause defense) |
The 40% gross valuation misstatement penalty is particularly significant — it doubles the penalty rate and applies automatically when the valuation claimed on the return is 200% or more of the correct value. Unlike the standard 20% penalty, the gross valuation misstatement penalty is not subject to the reasonable cause defense unless the taxpayer can show that the valuation was based on a qualified appraisal and that the taxpayer made a good faith investigation of the value. The rules for the reasonable cause exception at the 40% level are narrower and more demanding than the general reasonable cause standard.
Defenses to the Accuracy-Related Penalty
The accuracy-related penalty is not automatic and is not inevitable. Congress and the Treasury have recognized that taxpayers should not be penalized when they have made a genuine effort to comply, or when the tax law is uncertain. There are three principal defenses.
Reasonable Cause and Good Faith (§6664(c))
Most Common DefenseThe accuracy-related penalty does not apply to any portion of an underpayment if the taxpayer shows there was reasonable cause for the position and the taxpayer acted in good faith. This is a facts-and-circumstances test — the IRS considers: the taxpayer's effort to assess the proper tax liability, the taxpayer's experience, knowledge, and education, reliance on the advice of a competent tax professional (if the taxpayer provided complete and accurate information), and the complexity of the tax issue. Reasonable cause is determined on a case-by-case basis. The taxpayer bears the burden of proving reasonable cause. A penalty that is assessed without a showing that reasonable cause was lacking is vulnerable to challenge.
Substantial Authority (§6662(d)(2)(B)(i))
Legal Standard DefenseThe portion of an understatement attributable to a position for which there is substantial authority is not subject to the substantial understatement penalty. Substantial authority exists when the weight of authorities supporting the position is substantial in relation to the weight of authorities contrary to the position. Authorities include: the Internal Revenue Code itself, Treasury regulations, revenue rulings, revenue procedures, tax treaties, court cases, and IRS notices and announcements. Private letter rulings and determination letters directed to other taxpayers are not substantial authority. If a court has ruled against the position and the ruling has not been overruled or reversed, substantial authority is generally lacking. The standard is less stringent than 'more likely than not' (greater than 50% probability) but more stringent than 'reasonable basis' (approximately 20-25% probability).
Adequate Disclosure (§6662(d)(2)(B)(ii))
Procedural DefenseEven if substantial authority does not exist, the substantial understatement penalty can be avoided if the position was adequately disclosed on the return and there was a reasonable basis for the position. Adequate disclosure means the taxpayer explicitly identified the position on the return — typically by attaching Form 8275 (Disclosure Statement) or Form 8275-R (Regulation Disclosure Statement), or by completing the relevant form in a manner that makes the position clear. A reasonable basis is a relatively low standard — approximately 20-25% probability of being sustained on the merits. This defense is essentially a procedural safe harbor: if you told the IRS what you were doing and had at least a colorable argument for it, the penalty for substantial understatement does not apply to that portion of the underpayment.
Reliance on a Tax Professional — When It Works
Reliance on the advice of a tax professional is one of the most commonly asserted — and most frequently misunderstood — defenses to the accuracy-related penalty. Under Treas. Reg. §1.6664-4(c), reliance on professional advice constitutes reasonable cause and good faith if, under all the circumstances, the reliance was reasonable and the taxpayer acted in good faith. To succeed, the taxpayer must show: (1) the advisor was a competent professional with sufficient expertise in the relevant area of tax law, (2) the taxpayer provided the advisor with complete and accurate information, and (3) the taxpayer actually relied in good faith on the advisor's judgment. The advice must be based on all pertinent facts and circumstances and must not be based on unreasonable factual or legal assumptions. Reliance on an advisor to prepare a return — without evidence that the advisor specifically considered and advised on the position — is generally insufficient.
The Supervisory Approval Requirement: IRC §6751(b)
One of the most powerful procedural defenses against the accuracy-related penalty is the requirement under IRC §6751(b) that the IRS obtain written supervisory approval before assessing the penalty. This requirement — enacted as part of the IRS Restructuring and Reform Act of 1998 — is not a mere formality. The IRS must show that the immediate supervisor of the individual making the penalty determination approved the penalty in writing before it was assessed. If the IRS cannot produce evidence of timely supervisory approval, the penalty is invalid and must be abated.
The timing of supervisory approval matters. Courts have consistently held that the approval must occur before the penalty is formally communicated to the taxpayer — not after the fact. In Chai v. Commissioner (851 F.3d 190, 2d Cir. 2017), the Second Circuit held that §6751(b) requires written approval before the first formal communication of the penalty to the taxpayer. In Graev v. Commissioner (149 T.C. 485, 2017), the Tax Court reversed its own precedent and held that compliance with §6751(b) is part of the IRS's burden of production in a deficiency case — meaning the IRS must introduce evidence of supervisory approval as part of its case, not as an afterthought.
Practical Significance
If you receive an accuracy-related penalty assessment, one of the first things your representative should investigate is whether the IRS complied with §6751(b). A surprising number of penalty assessments fail this requirement — particularly penalties assessed through the IRS Automated Underreporter program (CP2000 notices), where the approval process is sometimes not properly documented. If the IRS cannot produce the written supervisory approval, the penalty is invalid regardless of whether the substantive grounds for the penalty exist. This is a pure procedural defense and does not require proving reasonable cause or substantial authority.
How the IRS Assesses the Accuracy-Related Penalty
The accuracy-related penalty typically arises in one of two contexts: an audit examination, or the Automated Underreporter (AUR) program. In an audit, the examining agent identifies an underpayment and determines whether the statutory grounds for the penalty apply. If the agent proposes the penalty, the taxpayer receives an examination report (often a 30-day letter) that includes the penalty calculation and an explanation of the grounds. The taxpayer can then challenge the penalty through the IRS appeals process or, ultimately, in the U.S. Tax Court.
In the AUR context — which generates the familiar CP2000 notice — the IRS computer-matches information returns (W-2s, 1099s, K-1s) against the income reported on the return and identifies discrepancies. If the discrepancy results in a proposed additional tax assessment, the IRS may also propose the accuracy-related penalty. CP2000 cases involving the accuracy-related penalty deserve particular attention because the initial penalty determination is often made automatically based on dollar thresholds and may not reflect a meaningful evaluation of the reasonable cause or substantial authority defenses.
Once assessed, the accuracy-related penalty is subject to the same collection mechanisms as the underlying tax — liens, levies, and garnishments. Interest accrues on the penalty from the due date of the return (including extensions). This means the penalty itself grows over time until it is paid or successfully challenged.
How to Challenge the Accuracy-Related Penalty
Challenging an accuracy-related penalty requires a strategy tailored to the specific grounds the IRS has asserted and the procedural posture of your case. There are several avenues:
Request Penalty Abatement Based on Reasonable Cause
File a written penalty abatement request (or Form 843) explaining why you exercised ordinary business care and prudence. Attach documentation supporting your claim — records showing reliance on a tax professional, evidence of the complexity of the issue, or other facts demonstrating good faith. The IRS will review the request and issue a determination.
Assert Substantial Authority or Adequate Disclosure
Identify the specific legal authorities that support the position you took on the return. Cite statutes, regulations, revenue rulings, and court cases. If you adequately disclosed the position on the return, identify where and how. This is particularly effective for substantial understatement penalties where the legal issue is unsettled.
Challenge Supervisory Approval Under §6751(b)
Request that the IRS produce the written supervisory approval for the penalty. If the IRS cannot produce it — or if the approval was obtained after the penalty was first communicated to you — assert that the penalty is procedurally invalid. This is a pure legal defense that does not require proving your substantive position was correct.
Appeal Through the IRS Office of Appeals
If the penalty is sustained at the examination or AUR level, you have the right to appeal to the IRS Office of Appeals. Appeals officers evaluate cases based on the hazards of litigation — meaning they consider the likelihood the IRS would prevail if the case went to court. A well-documented reasonable cause or substantial authority argument can persuade an appeals officer to concede the penalty even if the examining agent did not.
Petition the U.S. Tax Court
If the penalty is included in a statutory notice of deficiency (90-day letter), you may petition the U.S. Tax Court for review. The IRS bears the burden of production on the penalty — meaning it must present evidence that the statutory grounds apply and (for the §6751(b) issue) that supervisory approval was obtained. In the Tax Court, the procedural and substantive defenses can be litigated fully.
How the Accuracy Penalty Differs from Other IRS Penalties
Taxpayers often conflate the accuracy-related penalty with other IRS penalties. Understanding the differences is important because the defenses, procedures, and abatement options are different for each penalty type:
| Penalty Type | IRC Section | Rate | FTA Eligible? | Key Defense |
|---|---|---|---|---|
| Accuracy-Related | §6662 | 20% / 40% | No | Reasonable Cause, Substantial Authority |
| Civil Fraud | §6663 | 75% | No | Challenge IRS proof of fraud |
| Failure-to-File | §6651(a)(1) | 5%/mo (max 25%) | Yes | Reasonable Cause, FTA |
| Failure-to-Pay | §6651(a)(2) | 0.5%/mo (max 25%) | Yes | Reasonable Cause, FTA |
| Estimated Tax | §6654 | Interest-based | No | Statutory exceptions, waiver |
The most important practical distinction: First-Time Abatement (FTA) — the simplest and most common penalty relief program — does not apply to the accuracy-related penalty. You cannot call the IRS and request FTA for an IRC §6662 penalty. The defenses to the accuracy-related penalty are substantive legal defenses that require analysis, documentation, and persuasive argument — which is why professional representation is particularly valuable for this penalty type.
Key Takeaways
The accuracy-related penalty under IRC §6662 is a 20% penalty on underpayments attributable to negligence, substantial understatement of tax, substantial valuation misstatement, or substantial overstatement of pension liabilities.
The penalty increases to 40% for gross valuation misstatements where the claimed value is 200% or more of the correct value — and the reasonable cause defense is narrower at this level.
Three principal defenses: reasonable cause and good faith (a facts-and-circumstances test), substantial authority (legal authorities support the position), and adequate disclosure (the position was disclosed on the return and had a reasonable basis).
The IRS must obtain written supervisory approval before assessing the penalty under IRC §6751(b). Failure to do so invalidates the penalty — a powerful procedural defense.
First-Time Abatement (FTA) does NOT apply to accuracy-related penalties. The defenses are substantive and require documentation and legal argument.
The accuracy-related penalty is assessed on top of the tax and interest — a $50,000 underpayment results in a $10,000 penalty (at 20%) plus the tax itself plus interest from the original due date.
Facing an Accuracy-Related Penalty?
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New Beginning Tax Solutions is a private tax resolution company and is not affiliated with the IRS or any government agency. This article is for educational purposes only and does not constitute tax or legal advice. Results vary based on individual facts, income, assets, tax history, and IRS eligibility rules.