IRS Assessment Statutes: The Three-Year Rule, Six-Year Rule, and Open-Ended Exceptions

The assessment statute limits how long the IRS generally has to assess additional tax. It is not simply an “audit deadline,” and the calculation depends on the return, filing date, tax type, omissions, fraud, extensions, and other statutory rules.

The General Three-Year Period

For many income-tax returns, the IRS generally has three years after the return was filed to assess additional tax. A return filed before its statutory due date generally is treated as filed on the due date for this purpose. A late-filed return generally starts the period when it is actually filed. The exact rule can differ for other taxes and returns.

When Six Years May Apply

A six-year period may apply when a taxpayer omits more than 25% of gross income, subject to statutory definitions and disclosure rules. Special six-year provisions also apply to certain omissions involving foreign financial assets. The calculation is not always based on net profit, and adequately disclosed items may be treated differently.

When the Period May Remain Open

The assessment period generally does not begin for a return that was never filed. A false or fraudulent return filed with intent to evade tax, or a willful attempt to evade tax, can also leave the assessment period open. Whether a submitted document qualifies as a return can itself be disputed.

Extensions, Amended Returns, and Special Rules

A taxpayer and the IRS may agree in writing to extend the assessment period, typically on Form 872 or a related form. Filing an amended return generally does not restart the entire statute, although an amended return showing additional tax within the final 60 days can extend the period for assessing that additional amount. Partnerships, employment taxes, estate and gift taxes, foreign information reporting, and listed transactions may involve separate rules.

An examination may begin near the end of the statute, but the IRS generally must assess within the applicable period unless the period is suspended or extended. Transcript dates, return copies, signed extension forms, and the governing statute should be reviewed together before relying on an expiration date.

This article provides general federal tax information. Statute calculations are deadline-sensitive and should be confirmed using the actual filing and account history.