Can the IRS Assess Tax After Three Years for Fraud? What the IRS Must Prove

Yes. If a return is false or fraudulent with intent to evade tax, section 6501(c)(1) lets the IRS assess the tax at any time, not just within the usual three years. But the IRS has to prove that fraud, and in Tax Court it must do so by clear and convincing evidence for each year; a mistake, or even a large omission, does not by itself remove the deadline.

That question kept a tax preparer’s 2008 and 2009 years open until 2019 in Pinckney v. Commissioner, T.C. Memo. 2026-113. Here is how to test an IRS claim that your deadline does not apply.

Which deadline is the IRS relying on?

Each rule has its own trigger and calls for different records.

The notice of deficiency also matters. Once mailed, it suspends the period while you can petition the Tax Court and, if you do, until the decision is final, plus 60 days (section 6503(a)). A notice mailed after the period has run comes too late, unless an exception keeps the year open.

Our reading: A transcript date is an IRS record entry, not the legal answer. In Pinckney, IRS account records showed assessment deadlines in 2013 and 2015, yet the court held the years open in 2019 because it found fraud.

What the IRS must prove to use the fraud exception

Section 7454(a) puts the burden of proving fraud on the IRS, and the Tax Court requires clear and convincing evidence. That is a higher bar than the more-likely-than-not standard that usually governs a deficiency. As the court applied it in Pinckney, the IRS must show two things for each year:

• An underpayment exists. Not the exact amount, but some underpayment, proved with the IRS’s own evidence. Your failure to substantiate a deduction does not satisfy this element.
• Some part of it was due to fraud. Direct proof of intent is rare, so the IRS may rely on circumstantial evidence and the taxpayer’s entire course of conduct.

The same finding carries the civil fraud penalty: 75% of the part of the underpayment attributable to fraud (section 6663(a)). Once the IRS proves any part fraudulent, the entire underpayment is treated as fraudulent except a portion the taxpayer proves, by a preponderance of the evidence, was not (section 6663(b)).

If the audit was suspended or a criminal case followed

The Internal Revenue Manual tells an examiner who finds firm indications of fraud meeting criminal criteria to suspend the examination without telling the taxpayer why. If the taxpayer asks whether a fraud referral is being considered or Criminal Investigation is involved, the examiner must not give a “false or deceitful response.”

Suspending the examination did not stop the clock in Pinckney: The usual three-year periods expired during the criminal case, and the IRS could assess later because it proved fraud. Our reading: That makes a request to sign an extension during an audit a real decision; section 6501(c)(4)(B) requires the IRS to tell you of your right to refuse or to limit the extension to particular issues or a particular period.

The criminal case can also become civil evidence. In Pinckney, the court found intent from a cost-of-goods entry a service business could not have had, the same false entry on customers’ returns, a guilty plea and sworn trial testimony.

Records to gather now

• The original return and filing proof for each year, plus IRS account transcripts. In Pinckney the IRS recorded a 2009 return as received more than five months after it was filed, which changes the date arithmetic.
• Every signed extension consent and the IRS letter that requested it.
• Each 30-day letter and the notice of deficiency. They show which theory the IRS used and when, and by whom, the fraud penalty was first proposed in writing.
• Bank statements, deposit slips and check images. If the IRS later rebuilds income with a deposits analysis the notice did not describe, the court may treat it as a new matter on which the IRS bears the burden, as Pinckney did, and deposits it cannot trace can drop out. If the notice itself rested on deposits, you would have to prove which were nontaxable.
• Anything showing how each disputed entry was prepared: worksheets, source documents and messages with the preparer. Fraud is decided year by year, and once the IRS proves part of a year’s underpayment fraudulent, these records are how you show that other items were honest errors, which limits the 75% penalty but does not shorten the assessment period.