Final answer:
The usual statute of limitations for IRS audits is extended from three to six years if more than 25% of gross income is omitted on a tax return.
Step-by-step explanation:
The statute of limitations for a taxpayer who fails to report more than 25% of their gross income is not specifically addressed within the context provided; however, in general U.S. federal tax law, the statute of limitations is extended to six years if a taxpayer omits more than 25% of their gross income on their tax return.
Normally, the Internal Revenue Service (IRS) has three years to audit a tax return, but this period is extended when there is a substantial understatement of income.