The IRS audited approximately 582,000 individual tax returns in fiscal year 2024 — a rate of about 0.44%. While the overall odds of audit are relatively low, certain return characteristics dramatically increase your risk. Understanding what triggers IRS scrutiny is the first step to filing a defensible return and avoiding the time and cost of an examination.
The IRS uses several methods to select returns for examination: the Discriminant Function System (DIF), which scores returns based on statistical deviation from norms; the Unreported Income DIF (UIDIF), which identifies potential underreporting; document matching through the Information Returns Processing (IRP) system (which matches W-2s, 1099s, and K-1s against return data); and targeted campaign audits focusing on specific industries or issues identified through compliance research.
The single strongest predictor of audit selection is income level. IRS data shows audit rates of 8.9% for returns reporting $1 million or more in total positive income — compared to 0.22% for returns reporting $25,000–$50,000. If you are a high earner, robust documentation and professional tax preparation are essential.
The DIF system flags returns where deductions appear disproportionate to income. Charitable contributions that exceed 10% of AGI, business meal deductions at the maximum rate, large home office deductions relative to reported income, and casualty loss deductions all invite scrutiny. This does not mean you cannot claim legitimate deductions — only that you must have documentation to support them.
Schedule C filers — sole proprietors — are significantly more likely to be audited than W-2 wage earners. The IRS knows that cash income and personal/business expense blurring are common among self-employed individuals. Schedule C returns showing losses for multiple consecutive years are a particular red flag, as is a Schedule C that consistently shows income just below a round-number threshold.
Since 2019, the IRS has included a cryptocurrency question on Form 1040. Failure to answer accurately — particularly answering "No" when you had taxable transactions — is a significant audit risk. The IRS receives transaction data from major exchanges under third-party reporting rules, and cross-referencing this with return data is a priority enforcement area in 2026.
The home office deduction is frequently abused and is a known audit trigger. To be deductible, the space must be used regularly and exclusively for business — not occasionally, and not for personal activities. Since the COVID-era work-from-home boom, the IRS has increased scrutiny of this deduction, particularly for W-2 employees (who generally cannot claim it).
Claiming 100% business use of a vehicle is almost always a red flag — the IRS knows most vehicles have at least some personal use. Contemporaneous mileage logs are essential. GPS records and business appointment calendars are strong supporting evidence.
EITC claims have historically had high error rates. The IRS audits EITC claims at a higher-than-average rate as part of its anti-fraud efforts. Changes in family composition, income near phase-out thresholds, and self-employment income qualifying for EITC are all risk factors.
The IRS receives millions of information returns (W-2s, 1099s, K-1s) annually and matches them against filed returns. Failing to report income that the IRS already knows about through third-party reporting — whether freelance income, investment income, or gambling winnings — is one of the highest-certainty paths to a CP2000 notice or audit.
| Audit Trigger | Risk Level | Documentation Required |
|---|---|---|
| Income over $1 million | High | All income records; professional preparation |
| Large charitable deductions | Medium-High | Receipts, appraisals for non-cash donations over $500 |
| Schedule C with losses | High | Profit motive documentation; business records |
| Crypto transactions | High | Exchange statements, cost basis records, Form 8949 |
| Home office deduction | Medium | Floor plan measurements, exclusive use evidence |
| 100% vehicle business use | High | Contemporaneous mileage log; business purpose records |
| Unreported 1099 income | Very High | Report all amounts; reconcile with records |
Receiving an audit notice does not mean you owe additional tax. Most IRS audits are correspondence audits — conducted by mail — and many are resolved by providing the requested documentation. If you receive an audit notice: do not ignore it, respond by the deadline, gather your documentation, and consult a CPA, enrolled agent, or tax attorney before responding. You have the right to professional representation in any IRS proceeding.